In 1962, Thomas Kuhn wrote a seminal book entitled The Structure of Scientific Revolutions in which he introduced the term "paradigm shift." He argued that in science change rarely happens in a steady incremental way. Rather, a generation of scholars operates out of a (tough, resilient) set of assumptions, a paradigm, and new information gets assimilated or explained within the paradigm. But gradually contradictory evidence accumulates until it reaches a tipping point, and what Kuhn called a "paradigm shift" occurs. Previously ignored patterns in the contradictions abruptly becomes clear, and the community toggles to a better paradigm that will guide inquiry until evidence accumulates and these assumptions, too, get revised. Kuhn wrote about the hard sciences, but scholars since have come to realize that a similar process can take place in other scholarly communities and even in individuals.

Just like the born again Christians who feel transformed by faith, those who feel freed from faith want to share their discovery with those they love. Many former Christians grieve the fact that their spouses, children, or dear friends are still embedded in what now appears as an enormous cult. But what are the options? Attempts at conversation often fail, bringing tears and conflict, even shunning or divorce. A couple of elderly scientists are not allowed to see their grandchildren because contact might lead the children astray. A mother laments that a grown daughter won't let her visit because of the mother's loss of faith. A college student who has been caught reading "spiritual pornography" isn't allowed to be with his younger siblings unattended. What is a former believer to do?

One thing we know does not help is arguing. Research shows that after an argument, both sides tend to be even more entrenched in their old positions. By lining up our best arguments, we are more likely to convince ourselves that we are right than to convince anyone else. Perhaps the best advice is to adhere to the formula that has worked well for other hidden and stigmatized minorities: Be out. Be yourself. The more negative the stereotype of nonbelievers, the easier it is to challenge that stereotype simply by being a decent human being. When it comes to explicit conversations about religion, try to arrange time to sit down and really talk through your changes rather than having the differences of opinion come up in bits and scraps. Lay out your own thinking, and then let it be. For those you love, either the paradigm shift will happen or it won't. It is not in your power to control anyone but yourself.

To make things even more complicated, each religion has what can be called an immune system. Because traditional Christianity is centered on orthodoxy, meaning right belief, the immune system consists of a set of teachings that guard against other beliefs or loss of belief. Christianity's immune system includes the following teachings:

· Doubt is a sign of weakness or temptation by Satan, the father of lies.
· False teachers (those whose theology differs) should be cast out.
· Believers should not be unequally yoked (partnered) with nonbelievers.
· Nonbelievers have no basis for morality, so their motives are suspect.
· If Christians act badly, the flaw is in the persons, not the religion.

Given that core beliefs are naturally resilient and given the power of messages such as these, it will come as no surprise that people go to extreme lengths psychologically to defend religious dogmas.

Even outside our personal information filters is a set of ring defenses: our communities. Who forwards you email? What magazines do you subscribe to? What shows do you watch? Because confirmation is so satisfying and contradiction is so uncomfortable, we surround ourselves with friends and colleagues and coreligionists who think like us. Often, we join groups that do the filtering for us: Democrats for America, The Nature Conservancy, Assemblies of God, The National Rifle Association. These groups provide a steady flow of information confirming and elaborating what we think we know--and ensuring that a lot of contradictory information never makes it anywhere near our brains. They let us short-cut. Instead of weigh the quality of arguments and evidence - we look at the source and either raise or lower a draw bridge.

In an even more impervious form of this, we form a group identity: I'm a Catholic. I'm a Republican. I'm an American. I'm a Woman. I'm Hispanic. I'm a Calvinist. Each of these identities creates what I call a tribal information boundary (TIB). TIB's are remarkable efficiency devices, allowing us to weave coherent story lines about the world around us. But for someone seeking to understand complicated realities, they can be tremendously costly.

When we actually allow ourselves to bump up against the limitations of our world view, when we acknowledge we've hit a wall and then find a way over or around it--that is when growth is most likely to occur. In the 1998 comedy, The Truman Show, the protagonist, played by Jim Carrey, pushes past an information boundary and realizes he is living in the artificial world of a television set. From childhood, Truman has accepted the explanations and roles offered him. But he is confronted with small discrepancies, and one day he ignores his own fears and barriers that his community has erected, and punches through to the world outside. The movie's message to us all: It is possible.

But whereas diseases spread passively, meaning people rarely try to infect each other, viral ideas, also known as "memes" spread by harnessing the human desire to share what we know and to learn from each other. Memes get transmitted through established social networks. They spread horizontally within a generation, and vertically from generation to generation. That is why specific religions are concentrated in one part of the world or another and children tend to have the same religion as their parents.

For developmental reasons, children are particularly susceptible to simply accepting the ideas of their parents and community. If a parent says stoves burn you, cars can squish you, and bathing keeps you from getting itchy, kids tend to do best if they simply trust what their parents say. Nature has designed children to be "credulous." This allows them to learn from the mistakes of their elders. It makes them more efficient in acquiring valuable information and adapting to cultural norms. It is also why evangelical parents are encouraged to convert their children. Research on identity development shows that if children can be contained within an enveloping religious community through their transition into young adulthood, few will ever leave. Bring up a child in the way he should go, and when he is old he will not depart from it. (Proverbs 22:6)

A successful religion needs to have the qualities of a successful virus. In a changing environment, this means it must have the ability to mutate and adapt. In the past, religions spread largely by edict and conquest. This is how Christianity spread throughout the Roman Empire and into the Americas. Today, though, religion is perceived as an individual choice and religions must gain share by proselytizing or attracting adherents. For any religion to grow now, it must be something that people are motivated to transmit to each other one on one or in small groups. This is why, today, the religions that are gaining mindshare are those that have strong proselytizing mandates and high birthrates. In the current environment, Christianity has been able to produce offshoots that need no edict or conquest.

Significantly, the religions that are growing right now are ones with strong copy-me commands. Evangelical Christianity is centered on what Christians call the Great Commission: "Go ye into all the world and preach the gospel to every creature, baptizing them in the name of the Father the Son and the Holy Ghost." In addition, just as the Roman church latched onto the strategy of competitive breeding (keep women home, sanctify a high birth rate), so Evangelicals have begun to explicitly add this form of copy-me command to the mix. By contrast, modernist Christianity is more often centered on what Christians call the Great Commandment: "Love the Lord your god with all your heart, soul and mind, and . . . love your neighbor as yourself." In a straight up competition, the copy-me command wins out, and in fact, evangelicals are gaining mindshare, while modernists are losing it.

But most theological fundamentalists have a more hybrid approach. They protect their children from external influence by home schooling or parochial schools, but don't mind accessing creationist materials from interactive websites. They expand in-house social services that include pop psychology. They promote hierarchy and sexism but are willing to have women and children as spokespersons for these views. They play up the risks of inquiry and doubt and use scientific findings and follies to make their arguments convincing. Fundamentalist populations resist ideological change, but they have learned to exploit popular culture, best business practices, new technologies, and even scholarship itself to maintain the survival of their beliefs.

Since a virus and host fit together like a lock and key, understanding viral ideas helps us to understand the human mind, and vice versa. Retro-viruses and influenza mutate rapidly, which makes it hard to develop immunizations against them. On the spectrum of religions, Christianity shows a similar flexibility, regularly spinning off new sects, denominations, and even non-denominational renegades. And yet each of these taps a familiar range of emotions and social mechanisms and is constrained by the cognitive structures that place bounds on human supernaturalism. Christianity has adapted to a broad range of human minds and cultures, a strategy that has resulted in success beyond the wildest visions of the patriarchs.

When asked about whether Evangelical Christianity might fit the pattern, Conway and Siegelman were reluctant to say yes. Today they admit, "In America today, increasingly, that line [between a cult and a legitimate religion] cannot be categorically drawn. . . Our research raised serious questions concerning the techniques used to bring about conversion in many evangelical groups."(p. 37).

Conversion is a process that begins with social influence. As sociologists like to say, our sense of reality is socially constructed. We will come back to this later. Suffice for now to say that missionary work typically begins with simple offers of friendship or conversations about shared interests. As a prospective converts are drawn in, a group may envelope them in warmth, good will, thoughtful conversations and playful activities, always with gentle pressure toward the group reality.

In revival meetings or retreats, semi-hypnotic processes draw a potential convert closer to the toggle point. These include including repetition of words, repetition of rhythms, evocative music, and Barnum statements (messages that seem personal but apply to almost everyone -- like horoscopes). Because of the positive energy created by the group, potential converts become unwitting participants in the influence process, actively seeking to make the group's ideas fit with their own life history and knowledge. Factors that can strengthen the effect include sleep deprivation or isolation from a person's normal social environment. An example would be a late night campfire gathering with an inspirational story-teller and altar call at Child Evangelism's "Camp Good News."

These powerful social experiences culminate in conversion, a peak experience in which the new converts experience a flood of relief. Until that moment they have been consciously or unconsciously at odds with the group center of gravity. Now, they may feel that their darkest secrets are known and forgiven. They may experience the kind of joy or transcendence normally reserved for mystics. And they are likely to be bathed in love and approval from the surrounding group, which mirrors their experience of God.

The conversion process as I have described it sounds sinister, as if manipulative groups and hypnotic leaders deliberately ply their trade to suck in the unsuspecting and take over their minds. I don't believe this is usually the case. Rather, natural selection is at play. Over millennia of human history, religious leaders have hit on social/emotional techniques that work to win converts, just as individual believers have hit on spiritual practices they find satisfying and belief systems that fit how we process information. Techniques that don't trigger powerful spiritual experiences simply die out. Those that do get used, refined, and handed down.

With few exceptions the evangelists, from mega-church ministers to "friendship missionaries," are unaware of the powerful psychological tools they wield. They are persuasive in part because they genuinely believe they are doing good. After all, they have their own born again experiences to convince them that they are promoting the Real Thing. Consider, for example, the Apostle Paul, whose Damascus Road event (possibly a temporal lobe seizure) transformed his moral priorities and sustained a lifetime of missionary devotion. What decent person wouldn't want to share the secret to healing and happiness? The challenge is trying to figure out exactly what that secret is. As I say to my daughters, it is not enough to be well intentioned--even joyfully, generously so. We also have to be right.

When we overstate our ability to know, we play into the fundamentalist fallacy that certainty is possible. Burton calls this "the all-knowing rational mind myth." As scientists learn more about how our brains work, certitude is coming to be seen as a vice rather than a virtue. Certainty is a confession of ignorance about our ability to be passionately mistaken. Humans will always argue passionately about things that we do not know and cannot know, but with a little more self-knowledge and humility we may get to the point that those arguments are less often lethal.

For many reasons, religious beliefs are usually undergirded by a strong "feeling of knowing." Set aside for the moment the question of whether those beliefs tap underlying realities. Conversion experiences can be intense, hypnotic, and transformative. Worship practices, music and religious architecture have been optimized over time to evoke right brain sensations of transcendence and euphoria. Social insularity protects a community consensus. Repetition of ideas reinforces a sense of conviction or certainty. Forms of Christianity that emphasize right belief have built in safeguards against contrary evidence, doubt, and the assertions of other religions. Many a freethinker has sparred a smart, educated fundamentalist into a corner only to have the believer utter some form of "I just know."

Does this mean that rational argumentation about religion is useless? The answer may be disappointing. Religious belief is not bound to regular standards of evidence and logic. It is not about logic but about something more intuitive and primal. Arguments with believers start from a false premise -- that the believer is bound by the rules of debate rather than being bound by the belief itself. The freethinker assumes that the believer is free to concede; but this is rarely true. At best the bits of logic or evidence put forth in an argument go into the hopper with a whole host of other factors. And yet each of us who is a former believer (we number in the millions) reached some point in our lives when we simply couldn't sustain our old certainties. Our sense of knowing either eroded over time or abruptly disappeared. So sometimes those hoppers do fill up.

Given what I've said about knowing, how can anybody claim to know anything? We can't, with certainty. Those of us who are not religious could do with a little more humility on this point. We all see "through a glass darkly" and there is a realm in which all any of us can do is to make our own best guesses about what is real and important. This doesn't imply that all ideas are created equal or that our traditional understanding of "knowledge" is useless. As I said before, our sense of knowing allows us to navigate this world pretty well -- to detect regularities, anticipate events and make things happen. In the concrete domain of everyday life, acting on what we think we know works pretty well for us. Nonetheless, it is a healthy mistrust for our sense of knowing that has allowed scientists to detect, predict, and produce desired outcomes with ever greater precision.

The scientific method has been called "institutionalized doubt" because it forces us to question our assumptions. Scientists stake their hopes not on a specific set of answers but on a specific way of asking questions. Core to this process is "falsification" -- narrowing down what might be true by ruling out what can't be true. And to date, that approach has had enormous pay-offs. It is what has made the difference between the nature of human life in the Middle Ages and the 21st Century. But knowledge in science is provisional; at any given point in time, the sum of scientific knowledge is really just a progress report.

Because our theory of mind is so rich, we tend to over-attribute events to conscious beings. Scientists call this hyperactive agency detection. What does that mean? It means that when good things happen somebody gets credit and when bad things happen we look for someone to blame. We expect important events to be done by, for and to persons, and are averse to the idea that stuff just happens. We also tend to over-assume conscious intent, that if something consequential happened, someone did it on purpose.

This set of default assumptions explains why the ancients thought that volcanoes and plagues must be the actions of gods. Even in modern times, we are not immune from this kind of attribution: Hurricane Katrina happened because God was angry about abortions and gays; the Asian tsunami happened because he was disgusted with nude Australian sunbathers. If gods are tweaking natural events, then we want to curry their favor. Around the world, people make their special requests known to gods or spirits by talking to them and giving them gifts. Athletes huddle in prayer before a game, just in case those random bounces aren't random. After a good day at the casino, a thank-you tip may go into the offering basket. Or it may be that the offering goes into the basket beforehand.

All of this builds on the idea that gods or other supernatural beings are akin to us psychologically. They have emotions and preferences. They take action in response to things they like and dislike. They experience righteous indignation and crave retribution. They like some people better than others. They respond to our loyalty by being loyal to us. They can be placated or cajoled. They like praise, affirmation, and gratitude. They track favors and good-will in a kind of tit-for-tat reciprocity.

Abstract theologies are a fairly recent invention in the history of human religion, and they tend not to govern religious behavior. Even people who describe their god as omniscient or who insist that everything is predestined actually behave as if they need to communicate their desires and can influence future events by doing so. The god of Christian theology and the god that ordinary Christians worship are two different creatures.

If the structure of our minds predisposes us to certain kinds of religious beliefs, it also precludes others. Nowhere in the world is there a supernatural being who exists only on alternate Tuesdays, or who sees everything but forgets it all in ten minutes, or who rewards us for ignoring and disobeying him. Nowhere is there a god who knows the future, but only the next hour, or a god who starves people to death whenever he is pleased with them, or who is exactly like an ordinary person in every way. Some ideas are simply not interesting to us. They may be counter-intuitive in ways that make them forgettable instead of "sticky." Maybe they don't make good stories or maybe we don't have good places to file them in our index of memories.

According to Pascal Boyer, a good religious concept must strike a balance between being interesting and expected. It must activate an existing ontological category (let's say "river"), add some counterintuitive tag (when dark and bubbling river turns to blood and heals people), and retain the default assumptions of the category except those that are otherwise specified (river is wet, flows, is longer than it is wide, has a bottom, etc.) We start with a familiar class of being or object then tweak it to pique our interest but leave intact our other basic assumptions about that kind of object or being. If the supernatural thing we are discussing is a conscious being, it also needs to have a basically human mind. Only under these conditions will it stick and get passed from one person to another. (Religion Explained)

Christian beliefs are highly successful at getting retained and transmitted. They fit our information processing structures and yet are counterintuitive in intriguing ways. They capitalize on our tendency to attribute events to human-like causal agents who have minds much like our own. They allow us to take machinery that is designed for processing social information and apply it to the problems of understanding inanimate objects and natural phenomena. They leverage our tendency to see patterns in ambiguous or random events. Consequently they are intuitive and broadly applicable and are easily remembered.

Each axis is in effect a question: can we know God or facts about God? (the Gnosis axis), and does god exist? (the Atheist/Theist axis). Here is my concern - can we say anything about God's existence or not if we deny that the question of God is a knowable one, which is the agnostic position or perspective? I say that we cannot. I have absolutely no idea what a "weak theism" could be - do they believe in God's existence but think that the question is unanswerable? It's not enough to say they have faith God exists but think that is not knowledge - they are taking a firm position, and that counts as an epistemic commitment.

If the axes are simple binary choices, then no theist can be "below" the line of knowledge. If they believe God exists, then they have implicitly or explicitly taken a position on the knowability of God. But more realistically, if we treat the axes as degrees of certainty or likelihood (from -1 for complete rejection to 0 for ambivalence, to 1 for complete acceptance) then anything "below" the line is agnosticism. And if you think that you cannot know what the strue about God (as I do) then neither atheism nor theism are positions you will take.

Why agnostics like myself reject the appellation of "weak atheism" is that we do not take any position on whether God exists or not, because we think it is simply an unanswerable question. And being told, as we are, by atheists who do take a position on the existence of God, that we are atheists is to basically deny our most fundamental commitment - that these questions admit of no reliable, knowable or testable solution. Hence, we get a bit snarky.