If you can cite some evidence for your belief, but not so much evidence that your belief is justified, I would say that still counts as faith. e.g. People who believe in the healing power of prayer can usually cite anecdotal evidence that prayer works, and this evidence strengthens their belief. But since their evidence is scarce and subjective, the belief is still considered to be faith.

In the theist example you raised, I agree that his faith is blind. "Believing in x gives me a sense of security" doesn't constitute rational grounds for believing in x; someone who believes in x for that reason alone would be believing on blind faith.

But in reality, people often have more than one reason for believing in something. If some of those reasons do support the truth of their belief, then their faith isn't blind. Let's say the theist believes in his religion for these five reasons:

1. Most of the people he trusts - his family, his friends, his religious community - have told him all his life that this religion is the truth.

2. He's read the holy book and finds many of its teachings to be wise and sensible, and hence supposes that all of its teachings - including ones asserting things he wouldn't otherwise have believed - are probably wise and sensible.

3. He's heard arguments for the truth of his religion and found them convincing, whereas opposing arguments sound less convincing to him.

4. He thinks adherents of his religion live better lives than other people.

5. He finds comfort and security in his religion.

1, 2, and 3 can all be considered evidence (even though the strength of the evidence is debatable). 4 and 5 are not.

He doesn't think he has irrefutable evidence that his religion's teachings are true, and he himself agrees that his belief is ultimately a matter of faith. But he does have some evidence, and the evidence he has strengthens his belief. Thus his faith isn't blind.

Valid evidence by whose standards?

Also, I don't think the question is faith in regards to religion, but merely faith in general. And, no, coorelation is by no means a substitute for actual proof, but it is entirely relevant to belief, and, sometimes, more impressive than fact. Without faith, science, truthfully? Would not exist. For science to exist, we must have be able to find, in our own minds, a REASONABLE amount of evidence that our science will yield worthwhile results. And what palpable evidence is there that it certainly will? I would be willing to say, in most cases, none. A hypothesis is all a scientist can logically conclude upon BEFORE science occurs - and a hypothesis is SPECIFICALLY reliant upon one thing - a faith based in reason and coorelation, but NOT proof. Proof is the child of science, and science is a child of faith.

Religion, then, is just one step behind science. Religion cannot yield proof. Religion, by definition, is a product of faith and belief. But these are, for the most part, reasonable evidences, even if, no, I do not agree with them.

On the opposite hand of reasonable faith, there is blind faith. Faith entirely marred in itself is blind faith.