People believe what they want to believe until they are faced with an undeniable truth. Belief is always a choice until actual proof is manifested. People with no proof whatsoever believe that there is no God. The Bible calls them fools. People also believe there is a God with no proof. Are they fools also? Not necessarily. We begin the search for the truth of God based on choosing to believe (in fact we must begin this way). But we cannot have an ongoing reletionship with God without FAITH. And faith is not (as some unbelievers claim) just blind belief. Faith is knowing. In fact, the Bible says that faith is evidence! God says that if we belileve (and act on that belief), then He will manifest Himself, thus turning "blind" belief into knowing faith.
Imagine a 5-year-old boy who believes that grass is green, but has never seen grass himself. Someone tells him that grass is purple. He says, no, it's green. The person says again that it's purple and proceeds to convince the boy of this. If that person's words are convincing enough, the boy will believe that grass is purple. But there are two questions: Does he believe the truth? (No, he believe the words of the person). Does what he believes happen to be the truth? (No, grass is not purple).
Five years later, someone new tells the now ten-year-old boy that grass is orange. He says no, it's purple. If this person has more convincing words than the other person, then the young man now believes that grass is orange; otherwise he continues believing it's purple. The same two questions aply: Does he believe the truth (No, he still believes someone's words) and does what he believes happen to be true? (No, grass is not orange).
Five more years pass and yet another person tells the fifteen-year-old that grass is green. He disagrees, saying it's either orange or purple, depending on which of the first two persons had the more convincing words. If this person convinces him to believe that grass is green, how would that affect the two questions? Well, does what he believes happen to be the truth? (Yes, grass is green). But, does he believe the truth? (No, he still believes someone's words). If you think it makes no difference, you are wrong. Why? Because all it will take is for yet another person to come along with more convincing words and the young man will then believe that grass is some other color.
If, however, the last person shows the young man where he can go to actually find grass and see it for himself, then the young man will be face to face with the undeniable truth that grass is green. He will believe the truth, and he will believe it because it's true, not because he was talked into believing. And from that moment, nothing anyone ever tells him will change his belief, because he has perceived the reality for himself. This is what faith is like.
So it is with faith in God. Many people today say they believe in God, but they only believe what they have been told by someone else; they have not actually experienced God's reality for themselves. Therefore, their faith is weak, because Jesus is not the author and finisher of it; the author of their faith is whomever they chose to believe. We cannot live lives that are pleasing to God with this kind of carnal faith, which is really nothing more than belief, blind belief at that, because the person hardly knows enough about God to fully trust the idea that he can completely put his or her life into God's hands!
The Bible promises that if we seek God with all our heart, diligently, and if we act on the simplicity of belief and find out what God wants of us, and if we commit to give it to Him, He will make Himself absolutely real to us. This is not the promise of Christianity, nor the promise of the Church; it is the promise of God Himself. No Saint has any reason to have to try to build a life of holiness on blind faith; it can (and should) be built upon a substantial, evidential faith as defined in Hebrews 11:1.