Do any religions have bad teachings in their holy book(s) and/or history?

[TlalocW]

9. The Bible endorses slavery

Exodus 20 is all about how Hebrews are to get their slaves from the surrounding tribes (slaves, no indentured servitude) and how you can beat them as badly as you want as long as they can get up and walk in a couple days. Then for the male Hebrew indentured servants, if you want to keep them as slaves, you can find them a wife from your female slaves, and at the end of their servitude, they can either leave without the wife (and any kids born from the marriage), or he can have an awl driven through his ear as proof that he wishes to remain as a slave to continue being with his family. And of course, they get passed down like any property to the original slave-owner's kids.

There's the whole flood thing. I always found it pretty stupid that an all-knowing, all-powerful being's best solution to dealing with sinful humankind was to wipe them all out in a flood, making them suffer by making them drown (so much for all-merciful). I believe an all-powerful God could Thanos-snap people out of existence.

And finally, Hell - an infinite punishment for a finite sin.

TlalocW