Religion is not science so it cannot be tested or predictive in a scientific way.
There is a rational justification for faith because without faith one could not believe in God since God does not provide proof of His existence.
Sounds suspiciously circular...
This presupposes the existence of a God and the necessity of a mechanism to believe in Him.
All you're saying is that without faith (belief-without-evidence) you could not believe in God, therefore, faith must be reasonable. Therefore, God must exist.
The fact that God does not provide proof of His existence does not mean God does not exist. There is no reason to think that God would provide proof, especially if God wants our faith.
So God prefers faith to knowledge?
He could easily reveal Himself, but He wants to separate the rational from the irrational -- and prefers the latter?
God does provide evidence of His existence by way of the Messengers He sends who reveal scriptures. There is no proof that God spoke to these Messengers but there is evidence that indicates they did.
Messengers of God are a dime a dozen. Look in any mental hospital. Religious delusions are as common as grass. I see no reason to believe the religious mythology of the Christians any more than that of the Norsemen, Greeks, Aztecs or Muslims.
How does one reliably establish the veracity of a persons claim to divine revelation?
It requires some faith to believe in the Messengers since we cannot ever prove they got a message from God. However, that faith can be a reason-based faith, not a blind faith, if it is based upon proper investigation.
Investigation into what? What testable, falsifiable, peer-reviewed discoveries do you hope to uncover, that no-ones discovered before?
Sometimes faith is based upon sufficient evidence, sometimes not, it depends upon the religion.
If there were reliably evidenced 'faith', wouldn't it be generally accepted, like relativity? Why is there still religious diversity in the world?
However, there will never be proof that God exists because that's just the way God wants it to be. Logically speaking, an Omnipotent God could provide proof if He wanted to, so the logical inference is that God does not want to provide proof.
But this is just a facile rationalization, and describes a situation that would be identical if there were no God at all.
Why does God want to separate the reasonable from the unreasonable? Why does He prefer the unreasonable? Why does he give us brains at all? He could have made us any way He wanted.
That has not been a problem for the 93% of people in the world who believe in God absent proof. It is only a problem for atheists. However, since God does not need anyone's belief, God does not care if 7% of people remain atheists.
But that
has been a problem, and has caused or excused untold death and destruction over millennia.
What does this indifferent God think of all this carnage and misery? He does nothing to avert it. What does that say of His character?