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

[NeoGreen]

13. Another important point, there are no severability clauses...

...in the Bible.

Severability
In law, severability (sometimes known as salvatorius, from Latin) refers to a provision in a contract which states that if parts of the contract are held to be illegal or otherwise unenforceable, the remainder of the contract should still apply.

https://en.wikipedia.org/wiki/Severability

And consequently, if one finds that any part is found to be illegal or otherwise unenforceable, then one may toss the entire "word".

In fact, it is my understanding that the opposite is true, that there are essentially Inseverability clauses in the bible.

Matt 5:18: For truly I tell you, until heaven and earth disappear, not the smallest letter, not the least stroke of a pen, will by any means disappear from the Law until everything is accomplished.

Inseverability
Many laws have clauses specifying clearly the exact opposite, in which only all parts of the law taken together can be enforced: This act is to be construed as a whole, and all parts of it are to be read and construed together. If any part of this act shall be adjudged by any court of competent jurisdiction to be invalid, the remainder of this act shall be invalidated.

Falsus in Uno, Falsus in Omnibus!
A Latin phrase meaning "false in one thing, false in everything."

Toss it all!