I am just a human with many flaws
But it's not rational to judge an ethic or religious doctrine by the claimed adherents. People tailor their religions to fit their own values; they cherry-pick their scriptures. Even if the doctrine is true, it's purported followers will find ways to tailor it to their own ends.They are as "rational" as you or I are. They simply hold to a different criteria of rationalization.
I have a friend who was raised in a home with a violent, physically and emotionally abusive father. He, his sister, and his mother all suffered the ongoing abuse of this ogre for decades. When the family priest used to come to visit, for dinner, he would get my friend alone and sexually molest him. So did an older cousin. And no one ever did anything about it. Even the man who preached about salvation every Sunday was just another liar and abuser, doing as he pleased when no one was looking. So my friend grew up believing that the world is a very 'Darwinist' environment where the strong do as they please to the weak, and get away with it. And there will always be someone stronger. So the best thing we can do is try and appease the ogres and hope they attack and abuse someone else, instead of us, when the urge strikes them.
He spent his life working in a brokerage house, serving the greed of the rich and powerful (the ogres of our society), riding their coattails through the markets to gain a few extra shekels for himself, and hoping they would spare him from their abuse, as a loyal servant.
He has been a die-hard republican all his life, and will undoubtably vote for Trump a second time. And nothing I could ever say to him will ever dissuade him from his dark and dour view of humanity and of the world. Because all his experiences in life have shown him that his dark and dour view of existence is accurate, and that people like me are just "irrational" ideological fools, living in some pretty fantasy-land where the strong can't just do whatever they want to the week, for their own pleasure, and get away with it.
And I can't say that he's wrong. Only that he's not entirely right.
I'd judge the two separately.