I know that most men, including those at ease with problems of the greatest complexity, can seldom accept even the simplest and most obvious truth if it be such as would oblige them to admit the falsity of conclusions which they have delighted in explaining to colleagues, which they have proudly taught to others, and which they have woven, thread by thread, into the fabric of their lives." -Tolstoy
What's at stake when we consider religious ideas? Why is it that people change their religions at most once or twice per lifetime when really there is more religious thought out there than an expert could learn in twenty? Why don't members of doomsday cults leave when the doomsday date comes and goes without so much as a thunderstorm?
As they say, denial ain't just a river in Egypt. Even in science, whose praises I sing from this blog, people who should know better often refuse to accept new realities. Einstein, who himself revolutionized our understanding of the world more than anyone since Darwin, refused to accept quantum theory, saying famously "God does not play dice with the Universe." The great scientist Max Planck said, "A scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die and a new generation grows up that is familiar with it," and, more colorfully, "science advances funeral by funeral."
Maybe we have to want to change before we can accept truths which contradict our worldview. In Alcoholics Anonymous, there's the concept of "hitting rock bottom," before which people are unwilling to accept what AA offers. Maybe we all need to hit some sort of bottom before we're able to consider other views.
However, I think there are people who are seekers. I was one of them, and my quest led me to atheism. I did not know where I was going, only that I wanted to find out what was true more than I wanted to be comfortable. I know Orthodox Jews who became Orthodox Jews because that is where their quests took them, so I can't claim that atheism is special in that regard. Lots of Western intellectuals seem to find their way to Buddhism as well. I think that in the case of the seeker, he's born into a situation which does not fit and is driven to find the place he belongs.
So maybe there are two ways we change: we can be in such misery that we want to trade in our worldview for another, or we can have inherited a worldview we don't fit into. Or, maybe, we simply change so much that our old worldview no longer fits us and we must find another.
Anyway, none of this offers much hope for changing people's minds by debating on the internet. :-)