As a few people have pointed out, there’s something missing from my discussion of religion as the leading source of atheism. I said that when you find a mistake in your religion, you have two options: either leave the church, or become a hypocrite. The possibility of correcting the church’s error is not really an option, because the church’s whole authority system is predicated on the assumption that it cannot make any mistakes in the first place. Acknowledging the existence of an error means admitting that the church’s authority is based on a false premise.
Some people suggested that the third option is to start a new religion, or at least create a schism, but I would include that as a sub-category under the heading of leaving your old religion. When you start a new religion, or a new branch of the old one, you’re saying in effect that the old one is wrong and therefore you’re leaving it. I got to see this a lot in the Church of Christ: each half of the church split would promptly declare that the other half was on its way to hell, because they were rejecting the Bible’s plain declaration that _______ (fill in the blank: “communion is/isn’t one cup”,”missionary societies are/aren’t a permissible means of spreading the gospel”, etc). You may be staying within the broad outlines of religion, but you’re leaving your original faith.
As others pointed out, though, there is a third option, and it’s quite fascinating in a way. You can change a church founded on dogmatic tradition, provided you make the change retroactive. This is the Roman Catholic Church’s forte, but Protestantism is no mean hand at this game. The Church Council decides that God is a Trinity, and poof, the Christian church has always believed in the Trinity. Some pope decides that dead babies go to limbo? Poof, the church has always believed in limbo. Some American preacher decides that alcoholic beverages are sinful? Poof, the Bible has always declared that all alcohol is sinful. And so on.
That’s an ingenious, if disingenuous, means of solving the problem. You get to change what the church teaches, without undermining the dogmatic traditionalism, by simply revising the past to insert your new teaching into the original dogma, retroactively. And it happens a lot, even in churches that don’t make quite the stir over Apostolic Tradition as the Catholics do.
The problem is that the third option is also a tremendous source of deconversions. People aren’t necessarily any more stupid than they want to be, and when you decide to start redefining history in order to change doctrines without being honest about it, people notice. Schisms arise, and so do animosities. People fall away, unable to deny any longer that their church is simply manipulating the idea of “truth” in order to teach whatever they want, regardless of the facts. And when you realize that the religious leaders of the past (including the prophets and apostles) were just as human as today’s leaders, there’s no longer any reason to simply assume that whatever they tell you must necessarily be the truth.