Faith is a critical pillar in religions like Christianity. This entails treating not only doubt and skepticism as enemies, but also nonbelievers asking critical questions, offering reasons to doubt the reliability of religious claims. This attitude towards doubt may be an important reason why atheists and skeptics are so reviled by conservative evangelicals: the mere existence of atheists is a threat because they demonstrate a person can live and even thrive without faith in any gods.
George Smith writes Why Atheism?:
To say that atheism is credible is to suggest that the atheist may be right; to say that the atheist may be right is to suggest that the Christian may be wrong; to say that the Christian may be wrong is suggest that faith may be an unreliable guide to knowledge; to say that faith may be an unreliable guide to knowledge is to suggest that each and every tenet of Christianity should be reexamined in the light of reason — and from here all hell breaks loose as the process of deconversion rushes headlong to its logical destination.
Many have wondered why conservative religious believers react with such hostility towards atheism and atheists. There are some obvious reasons (atheism is thought to be immoral and an affront to God) and some less obvious reasons (hostility towards atheism is a legacy of the Cold War battle with godless communism). Here, however, we have a possible reason which not only might go unnoticed by atheists, but which many believers may also miss — and may not be consciously aware of.
One of the more honest comments I've ever received from a Christian actually admitted outright that a site like this is threatening precisely because it encourages skepticism, doubt, and uncertainty:
Why was I threatened? Your site raises questions about Christianity that shake my foundational belief in a loving creator... mainly because you show the shady dealings, illogic, and evil of people who call themselves Christian. Like a good sceptic, you plant doubt.
I'm sure this isn't true of all the Christians and religious theists who visit this site and disagree, but I wonder how many it is true of? Probably more than would be willing to admit it openly, even to themselves. This is not to say, though, that some don’t recognize on an unconscious level that it would be better if they didn’t have to seriously confront the possibility of being mistaken — that their beliefs are more secure so long as they can maintain the impression that being wrong is out of the question.
Inveterate opposition to doubt, skepticism, and the atheists who dare to foster such attitudes eliminates the need to deal with difficult questions and substantive challenges. It’s easier to focus on evidence and arguments which reinforce what they already believe rather than consider that atheists, even if mistaken, are at least mistaken for fair, honest, and reasonable reasons. This would mean that, even if true, their religion is not so unambiguously true or so unquestionably valid as they would like everyone to think.
The denigration of doubt goes further, though, and includes for example efforts to cover up anything which would cause people to doubt religious leaders and institutions. Scandals, crimes, and hypocrisy are swept under the rug "for the sake of the community" and uncomfortable truths are suppressed as much as possible. The flip-side of this is the promotion of falsehoods which are thought to bolster faith.
George Smith writes further:
In Christianity doubt stands opposed not to certainty per se, but to faith. To have faith, in a religious context, is to have absolute confidence in God and to trust his revelations unconditionally.
Thus, for the Christian to be uncertain of a divine revelation is bad enough, but to doubt that revelation is incomparably worse, because the latter implies a readiness to criticize that the former does not. ...to doubt the truth of a purported revelation is to challenge God himself, and this indicates a rebellious spirit ...In short, for the Christian to doubt the truth of a purported revelation is potentially to challenge the authority of the infallible God in whom she believes.
It is therefore religious doubt, not atheistic disbelief, that constitutes the greatest threat to orthodox beliefs, because doubt threatens to undermine a belief system from within.
This is why it is more important when dealing with believers to try to plant a seed of doubt than to actively promote atheism. There is little or no ethical and intellectual value to atheism alone; there is, on the other hand, tremendous ethical and intellectual value in skepticism, doubt, and critical thinking.
This is, of course, the purpose of the site — not to promote atheism or disprove alleged gods, as some Christians assume, but rather to promote skepticism and critical thinking in place of faith and credulity. Even if someone continues to be a theist and a Christian, they will be much better off if that is in the context of also being skeptical, doubting, and questioning.
I wonder if this is one reason why so many Christians insist that atheism if a faith? If faith is so important that even the "wrong" faith is less threatening than doubt, then “atheism as a faith” can be dismissed more readily than “atheism as a challenge, a question, and a doubt.” I don’t think it likely that many, if any, Christians actually think about the issue in these terms, but this doesn’t mean that the connection isn’t being made unconsciously.