How could my extremely intelligent friend be so close to 100% sure that what he believed was true? Because "It's just something you know deep down, like you know the sky is blue and you need to eat food to live and move your legs to walk."

Then how can so many people not believe?

"I don't know. Maybe they've deliberately suppressed their faith so they can do whatever they feel like. Maybe they're misusing reason to justify their own sinning. They've been doing it for so long they've forgotten how they started."

What about Muslims and Jews and others? "Any religion that teaches a sound morality may be better than none in the eyes of God. But way deep down non-Christians may know they're in error, that their religions are at best incomplete. I can't really answer the question."

Is the bible literally true? "What's obviously meant to be literally true is literally true. What's meant to be symbolic is symbolically
true. Humans wrote it, so even though God directed them in general it isn't perfect. The crucial things like the Ten Commandments and the Resurrection are absolutely true."

Did God hand Moses the Commandments carved on stone tablets? "I don't know. I wasn't there. He could have if he wanted to. He's God. Or he could have just inspired Moses."

How about Noah's ark? "I wasn't there. I wouldn't take the story literally, but symbolically it's true." What does it symbolize? "God ultimately punishes the wicked and saves the good."

Do you believe in evolution? "Sure I do." Why? "There's too much scientific evidence not to, and I don't see how it really conflicts with any crucial teachings."   

What about people who think it does? "They're wrong."

I believe that my friend is more or less typical of serious, church-going Christians.