Does the Bible Contradict Itself?

[Undeceived]

You said believing is done with the heart, not the mind. I'm unsure about what heart you are speaking and how it differs from the mind.

One can find 'logical' reasons for anything. The trouble lies in finding the right logic. For simplicity, let's narrow it down to two: believing in Christ and not believing in Christ. Each uses a different starting point. A nonbeliever uses "me" logic--self-interestedness. A believer uses selflessness logic. A nonbeliever thinks the answer lies within them (in the way that worldly religions require works for salvation). A believer sees that he needs outside help; or to put it another way, we don't have to fight alone. A nonbeliever is always thinking about other people's perceptions of them (Adam and Eve noticing their nakedness). A believer is too occupied with others' needs to care. As infants, we start out with "me" logic. The transformation takes place with help of the Holy Spirit, who fills us with unnatural thinking habits--because, of course, selflessness makes no logical sense in our world. We must be not attack atheists for not being logical, for in a worldly sense they are more logical than us. "If I want pleasures I have to go out and get them for myself. It's a dog eat dog world; I stop running and I'll be run over."
There is an unnatural (spiritual) logic. And it is not reached by the brain, for our brain is of earthly matter. It thinks only of itself, as it is inclined to do. We are the dog that seeks prey, that desires to be the alpha dog, because that is our only evident immediate purpose. The Holy Spirit is our trainer. He teaches us not to be ravenous wild beasts looking for the next meal, but self-controlled, disciplined persons. Our new logic tells us to trust our master--He knows what is best for us. He points out pleasures that are more lasting and fulfilling. This set of goggles is cleaner and more in line with the Truth of the world, and our intended purpose in it.
The transition between goggles is done with the heart, via the Holy Spirit.
1 Corinthians 2:6-16 explains this well. 9-10 quotes Isaiah, As it is written:
“What no eye has seen,
what no ear has heard,
and what no human mind has conceived”—
the things God has prepared for those who love him—
these are the things God has revealed to us by his Spirit.
And Romans 12:2,
“Do not conform to the pattern of this world, but be transformed by the renewing of your mind. Then you will be able to test and approve what God’s will is —his good, pleasing and perfect will.”