No doubt about it: there are many absolutely brilliant atheists. And there are lots of absolutely brilliant Christians. So we have extremely intelligent folks who have diametrically opposed beliefs. How can this be?
What causes atheism?
I believe God intentionally arranged things so that the scientific, historical, and philosophical evidence alone would be less than overwhelming to prove his existence and his authority. You have to want, to seek, to love ultimate truth, regardless of the consequences, to find it. Fortunately, God promises that those who seek him wholeheartedly will find him. Unfortunately, most folks don't want him, because they love sin and/or they think they know best how to live their lives (pride). To illustrate:
--Sir Julian Huxley, nicknamed "Darwin's Bulldog", was asked why the scientific community quickly embraced evolution, and he candidly responded, "I suppose the reason we leaped at The Origin of Species was because the idea of God interfered with our sexual mores."
--Jesus Christ once rebuked the religious leaders who rejected him because of their pride: "How can you believe, when you receive glory from one another, and you do not want the glory that comes from God?" You have to humble yourself to receive glory from God.
Who has more credibility?
The atheist scholar gathers facts to bolster his position, as does the Christian scholar. But I believe that the atheist has some credibility problems. First, he doesn't believe in an all-seeing Judge, so he has no motivation except pure altruism to honestly search for and propagate truth, and no human is constantly altruistic. In fact, I think Christians are far more likely to act altruistically. Second, when an atheist confidently asserts that he knows there is nothing in the universe except matter and energy (as Carl Sagan did shortly before he met his Maker), he probably hasn't inspected the entire universe to see if this is true. It's like saying, "I've never met a blue-eyed African American, so there are none." Those who have met blue-eyed African Americans, like I have, will disagree, but the doubter may keep doubting.
When the Bible says,
The fool has said in his heart, "There is no God,"
it's not speaking of a lack of intelligence. The Hebrew word translated "fool" here has a moral connotation, as in acting or believing foolishly.
Happy April Fool's Day to you all.