I can’t say that the desire for “credibility” is something I really desire or think about as a theist. My religious practice is not a scholastic exercise, it’s a relationship.
It’s like when I got engaged, the only person who was seeking “credibility” was the girl I was dating. I don’t think anyone on the outside of that relationship was asking me for empirical evidence to prove the love I had for her. I don’t recall anyone who cared to raise such challenges, and I wouldn’t have been interested in answering them if they did come up. It’s a relationship. If you don’t believe I loved the girl, that didn’t affect the situation I was in.
It’s not too different with God. If what I do and how I live is not evidence enough that I love this “God” I foolishly claim to believe in, so what? If I look like an idiot because I put trust in something you don’t, it’s no skin off my back. Besides, I can’t expect you to believe in what you can’t see or feel or touch.
I’m not longer one of Jehovah’s Witnesses who believes I have to challenge everyone else’s philosophies or ideologies or constantly be trying to convince you to adopt mine. If you’re not interested or don’t care, fine. I’m not bothered, really.
Do I wish all people could enjoy the kind of relationship I have with what I believe is a Real Person? Sure, but I don’t expect it.
I’ve seen people confronted with empirical evidence of things that were not supernatural. I saw a member of my family drink themselves to death and others smoke themselves to death because they didn’t want to believe in the medical data regarding their life choices. I’ve had close friends die of AIDS because they didn’t want to believe that their carelessness choices would ever turn them into a statistic. I even saw a relative beaten to death by his own sons because they were so wrapped up in drug abuse and the drug world. All these people had evidence beyond argument that they need to change their minds and their lives. There was nothing there they could not believe in. They just didn’t want to.
So do I think people will change to accept my beliefs even I transfigured before them and was carried off into the heavens by angels? Yeah, right! Even if that happened before the whole world, there would still be people who would not believe it because humans are capable of refusing even the hardest of evidence.
As someone once said: To those who believe no explanation is necessary; to those who do not believe no explanation is possible.
You found something that fills your cup and refreshes you? Great. So have I. But I have nothing to prove. Who wants to believe in it even if I could?
Again another wise voice pointed out that it is not that Christianity has been tried and found wanting; it is that it has been found difficult and left untried.