Eternal punishment is pointless.

[Smaug]

It has nothing to do with that. People believe in the faith they grow up with and some people convert to it for other reasons then you state. The bad qualities of god in each of these religions goes either unnoticed or is seen as part of God's wrath qualities which are seen worthy and high themselves or just accepted on faith. But it has nothing to do with the reasons you state.

While you're partially right I couldn't agree completely. Though my observation was more of a passionate one there's still an important point. The things you've said apply to mild believers who don't really care that much as to bring up God in their everyday lives on every possible occasion. And who don't care to follow a dogma which is obviously outdated. While the fundamentalists are different. When it comes to supernatural and spiritual concepts people don't sincerely believe things they are unable to accept at least subconsciously. So it's not God who forces people to be bigoted, it's people who choose such gods that fit their views (which they may do consciously or not). And it's not a one-time choice. A person may re-define God throughout their life to fit their current worldview. While some people may have been forced to accept some concepts in their childhood when they grow up and become more experienced in life they inevitably face contradictions in their beliefs (internal and/or external) and get a chance to decide for themselves what is worth following (and the converts are obviously fully responsible for getting into their fundamentalism themselves).

That was the spiritual side of the problem. But there's also a social side. Religion is a strong uniting power. Retaining dogmatic beliefs provides fundamentalists with some pretty serious psychological and social benefits. They have confidence in the future (as far as beyond their death), they have less decisions to make (even if only apparently), they have ultimate authority to back their every opinion (let us remember that the authority comes not only from a deity but more importantly from the community!) and a feeling of supremacy, and they have a rather close-knit community that they sincerely expect to support them. What do they get from leaving or changing their faith? They risk to antagonize their community in one way or another (which leads to all kinds of possible trouble) and potentially face heavy depression and other psychological problems. Let's not forget that fundamentalist ideologies are built upon heavy antagonization and imply dear consequences for those who dare to leave. Not speaking of said consequences, changing worldview alone is a daunting task and many choose to reject reality instead. To add to it humans are social beings and even without knowing with certainty they subconsciously feel the consequences of their social actions. That's why many fundamentalists choose 'the easy way'. They choose obvious benefits of psychological comfort and social support over possible struggle and distress (remember that this choice doesn't have to be completely conscious - I'd risk to say that there are really not much people who choose fundamentalism completely consciously).