Sounds like you're not very committed to keeping an open mind. Coming from a different background than the rest of us is no excuse to treat it as a handicap when it comes to understanding others.
I'm open to keeping an open mind. I just have to be given something I can work with. I can guess as to why people may feel a need to believe in some power or force greater than ourselves. But so far, I've only heard that people believe because that is how they were raised. But not so much why they themselves sought comfort in such a believe.
I postulated this theory to my mother, who is a Christian (not of a particular denomination though). What if she was God? What if everything in this universe was God, both living and inanimate. In this sense God wasn't an entity or a force, but rather was a vast consciousness of which each one of us was a small part. The questions we have then are not of individual beings seeking to understand where they come from, but rather the universe seeking to understand itself through us.
She thought this an interesting theory, and thought it was a very real possibility. It would be an explanation that could satisfy both atheists (as it could conceivably be scientifically tested) and the religious. A novel that I'm in the process of beginning to write is based on this theory, only on a much smaller scale (planetary instead of universal).
I don't know why you, as a gay man, don't see the worth in trying. What are allies for if you claim we "can't understand what it means to be gay"? I can't experience it the same way you can, but would anybody really be an ally if I couldn't understand what it means?
I don't think a person has to actually understand something to be supportive of it. I mean, I certainly can't understand what it means to be female because I'm not female (though there are some times I wish I was one tbh), I still want to do everything I can to support them and defend them when they are being attacked (like those who seek to control women's reproduction organs by denying them birth control or the right to have an abortion). I think it's one of the reasons why I have more friends who are female than male. They know that I would do anything to make sure they were treated as equals by individuals and groups and governments (and yes, even churches), and also that I don't have any ulterior motives in doing so like trying to get into their pants.
So yes, I think an ally can be someone who doesn't understand what it means to be who, or what, the other person is. Because understanding, to them, doesn't factor into their decision to support someone. What does motivate them is their sense of right and wrong, and their love for their fellow human beings.