Periodically in discussions with atheists, one runs across comments from the atheist something to the effect of ‘no one really becomes a theist who has thought the problem through. The only reasons anyone becomes a theist is due to irrational reasons.’
This criticism cannot be leveled against Anthony Flew. This man was, for most of his life, a prominent atheist. Flew was perhaps the most intellectually well-published atheist, having literally written the book providing the foundations for atheism. He debated against theists, and was a quite formidable opponent. If anyone had thought the issues through, it was Anthony Flew.
Flew denounced atheism a few years back, becoming a theist. He is not, as far as I know, a Christian, but denies atheism and believes there is strong evidence for the existence of a theistic God. His reasons may surprise you: he feels the scientific evidence for Intelligent Design compels him to believe in the existence of a theistic God, saying that he must go where the evidence leads. Flew also says:
It seems to me that Richard Dawkins constantly overlooks the fact that Darwin himself, in the fourteenth chapter of The Origin of Species, pointed out that his whole argument began with a being which already possessed reproductive powers. This is the creature the evolution of which a truly comprehensive theory of evolution must give some account. Darwin himself was well aware that he had not produced such an account. It now seems to me that the findings of more than fifty years of DNA research have provided materials for a new and enormously powerful argument to Design.
You can find a good online article about Flew’s change of mind here. A later, longer explanation can be found in Flew’s book There Is A God: How The World’s Most Notorious Atheist Changed His Mind.
At the very least, this should demonstrate that one can be a theist and have thought through all the various issues and made an intellectual decision for the existence of God.