All religions have been written by man. They've been either imagined by man, partly or wholly, or divinely inspired.
I can respect the possibility of divine inspiration because we see this process in action today, with literally millions of people who've gone through a near death experience (NDE). Their messages on retuning from what seems to be a spiritual realm, have been curiously consistent - and positive and simple.
NDE's have been known to occur for thousands of years, and they've been documented. However, today they're particularly common because medical technology has brought so many back from clinical death (learn here).
So what is my assertion?
I believe the most reasonable assumption we can make is that all religions, though very possibly divinely inspired at first, have been corrupted to a given degree. As long as men in power have been able to stand between messengers and texts, it would be naïve to think that the texts would not have been manipulated.
In turn, I believe that the right thing to do with any religion is to hold it at arms length. Let it inspire you where it might, but don't let it be your dictator. If you find something in the teachings that doesn't agree with you, then you should not be afraid to reject it.
If we don't operate like this, and instead accept scripture as absolute, then this can make us dangerous. Blind obedience to any apparent authority can of course be dangerous.
However, if you are deeply religious then I can appreciate you might ask yourself: If my religion has been corrupted, why then would my God allow such a thing to happen?
I can only speculate, but I have a suggestion. I suggest that corruptions are clues. It can be healthy to see authority fail, because it reminds us to think for ourselves. Corruptions can remind us to not believe in something just because it's written down and endorsed by the powerful. Corruptions tell us we should first follow ourselves - authoritative scripture, second.
So, we shouldn't be afraid to disagree when we disagree. There's no evil in that. There's no evil in believing what may not ultimately be right, if our intentions are clean and so our mistakes are honest. Just do your best. What more can be asked?
The most profound corruption?
This can only be my opinion, but I personally believe that the greatest corruption in our main religions is the idea of eternal damnation. Yet, the corruption is understandable...
The idea of hell was created in a time when our societies were typically savage. Strong deterrence was vital to hold things together. Hell was surely a scare tactic for social control - written by man, for man, and as I believe by no God. It was and is social engineering, not inspiration.
A process of rehabilitation (karma?) would make more sense over unimaginable and eternal vengeance, don't you think?
Note: I wanted to bring attention to the idea of damnation, because I don't believe that people can think straight on their faith with the threat of hell in their minds. The time for that ancient idea is over, I believe. We don't need it and it's shutting down thought. And further, look at the insensibility of it: If you believe what you believe yet only because you're afraid not to believe it, then can you honestly say you believe it at all?
