I have heard it argued by certain critics of Judeo-Christian tradition that a God who delivers salvation based on belief is behaving unreasonably, because disbelief in the Christian God is a stance that one can hold in good faith, even after making a serious and honest attempt to discover the answer.
That is a quote from a user on ChristianBoard. I appreciate the honesty of the question, and have often wondered myself, "Can a person be just as faithful in disbelief as in belief?" In one sense, yes they can. Even the Bible agrees. Remember, according to Revelation 3:15-16, God holds settled belief in God and settled disbelief in God as equally noble positions, although only one of those positions will render eternal reward and security. It is the wishy-washy "lukewarm" that will be vomited out.
But, there is more to it than just "belief v. unbelief". Belief is the Christian's apparatus used to see God. And God rewards those who use their belief in this way by revealing more and more of Himself to us. That is why Jesus used our sensory perceptions, metaphorically of course, as descriptions of what experiencing God is like "Taste and see that the Lord is good... He that has ears to hear, let him hear... etc" That is why I have a difficult time believing it when someone says they were once a Christian and now is an atheist. One has to exercise faith in God to become a Christian. And faith properly exercised WILL result in a revelation of Jesus Christ that is impossible to ignore. So for me, when someone says they were once a Christian, and through rational and logical thinking has become an atheist, it is like a man who goes swimming, and then consequently, through this rational thinking, refuses to believe in water.
To be quite candid about it, belief in God is easy for the Christian. Maintaining a perpetual belief that He is ultimately benevolent in all His ways is the Christian's challenge. If I doubted God's mere existence, I would seriously question the state of my own salvation. That is the very first thing God will make clear in the life of any sincere Christian. But He always seems to leave His benevolence open to interpretation of one's own environment and circumstances. The real threat to a Christian's faith isn't the voice that says, "Ah, so God doesn't exist after all.", but the voice that says, in the midst of turmoil and confusion, "So this is what God is like... Deceive yourself no longer."
It is quite natural really. What child, with their limited understanding of their own reality, doesn't not regard the restrictions imposed by adults as mere impediments to their own joy and happiness? It isn't until the child matures that he or she can begin to understand that the reason Daddy wouldn't let them use the mower, or the reason Mommy wouldn't let them use the kitchen knife, was actually to protect the child from a danger they didn't understand. We are in a similar position with God. What we see as God's oppressive hand could very easily be His protecting hand.
So the two compulsory requirements of faith from believers is to believe that He exists, and that He is benevolent. (Hebrews 11:6)
So "reasonable disbelief" is just that... reasonable. God can still use that. The lukewarm are those with a "visceral disbelief", whose belief in God fluctuates with the state of one's circumstances, health, emotional state, or even the state of their digestion. The church sometimes calls these unfortunate Christians, "Fair-Weather Christians". Their belief isn't based on logic, but on an visceral reaction to some circumstance. Whether it is a rejection of God based on a lost job, repossessed asset, or death of a loved one; or whether it is a presumptuous belief in God's benevolence due to currently being "on the mountain", it is precisely the same thing. The balanced, and true, Christian knows that God is still benevolent even when the temporal world is being stripped from them, one asset after the other, and they are also willing to being "pruned" by God when their temporal welfare becomes a little too stable.
So the true Christian knows that when God blesses with temporal security, they should accept the blessings with thanksgiving to God, and pass them forward when their needs are met. They also know, even in their most prosporous periods of their life, that trials are coming that may remove temporal security for a season. In fact, I would be concerned if I never perceived my temporal foundations growing shaky, or if I never experienced God's temporal blessings. A balanced Christian will experience this same balance from God.
Christians also know and understand God's chastisement. In fact, when God brandishes His whip, the true Christian will gladly expose his back, and drink in the pain. Not in some masochistic need to be beat down by God's retributive wrath, but in understanding His purpose. Though the whip's sting is deep, the Christian does not want it to stop until the lesson is learned, thoroughly. God's chastisement is not punitive, it is disciplinary. And when He is disciplining you, He will lay no stripe that isn't necessary. No throb of pain will be without purpose. Christians often pout at God's chastisement, when they should be rejoicing.
No circumstance shakes the true Christian's belief in God's benevolence.
On a side note, and back on the subject of reasonable faith, please keep in mind, the atonement was never meant so we could gain Heaven after we die. Eternal reward is a byproduct of Christianity. The atonement was to restore the fellowship Adam had with God before the Fall. And, as we grow and exercise an ever increasing faith, the restoration of that fellowship becomes increasingly more profound. There are those who achieved that fellowship so strongly, that all the "perks" of being a Christian became truly peripheral, and even irrelevant, to their communion with Jesus Christ. This fellowship with God is the house, comprised of the stones of the atonement, provision, peace, redemption, etc. The writer of Hebrews told us to abandon the elementary principles of Christ, and move on to perfection (Hebrews 6:1). That perfection isn't necessarily accumulating opinions, searching out all the correct doctrines of Christianity, or shaping one's theology. It is fostering an honest, thorough, and meaningful relationship with Jesus Christ. That, to me, is the proper application of Christian faith.