Exactly. You’re trying to compare things that people probably did 1500+ years ago with things that happened in our lifetimes. There’s no way to attain justice for actions that happened over a millennia ago, and it doesn’t really make sense to try.

If you want to convince people that organized religion is shit, I think you have a lot of good ammunition on hand, including some of the things that you mentioned. I’m not sure you’re going to turn people off to Islam by mentioning that Muhammad was a warlord, though.