Even if what you’re reading is Mein Kampf, because there are actually good reasons for reading Mein Kampf. The true believer is always concerned, both on her behalf and on that of other members of her ingroup, for mental purity. But as Jesus said, it is not what we take in that defiles us, it’s what we send out.
eh, actually, more often than not, you are what you read; ideas and notions normalize through repeated exposure, what was novel and weird becomes habitual, acceptable, finally fully accepted. garbage in, garbage out; most people aren't super rational and alert to bad thinking all the time.