Bad ideas can cause good people to do bad things.
The idea that some ‘ideas’ (books, ideologies, beliefs) should remain ‘uneditable’, is perhaps a good example of a bad idea.
Tolerance for ‘intolerance’ is perhaps another bad idea.
Some ideas are not intrinsically ‘bad’, they may have served a purpose some time ago, but we have now replace them with better ideas; the ‘flat earth idea’ might serve as such an example. Astrology has been supplanted by astronomy; alchemy by chemistry, etc.
In a bygone era, when we saw some people ‘over there’ that looked different than us, it might have been a very good idea to stay away and avoid contact with them. Nowadays though, our lives are usually improved by interacting with people who look and behave differently; diversity makes the world a far more interesting and wonderful place.
Ideas are wondrous things; they simply ‘appear’ in consciousness – so we can hardly be ‘blamed’ for having them. Thoughts and actions though … that may be another matter … (philosophical discussion required on this point).
There are bad ideas (or perhaps outmoded might be a better word) that we should shed; and good ideas that we should adopt. There are also just ‘new’ ideas; ideas we can try on, test, subject to rigour … and see how things turn out. It’s a wondrous, calamitous, sometimes dangerous, always interesting and ongoing experiment.