An open mind is like a fortress with its gates unbarred and unguarded.

Thoughts are viruses, memes. Most people are retards and not mentally strong enough to defend themselves from ideas on their own. That is why things like religion exist, to provide a layer of protection from harmful thoughts for people who lack the internal fortitude to reason through everything for themselves. However in the current world there has been a concerted attack on organized religion in order to subvert and destroy it so that people will be less resistant to hostile ideas.

If you live in a society that has weakened social defenses and is experience a non-stop assault from people utilizing these negative thoughts to weaken and destroy you, then having a closed mind is the best personal defense you can get.

Me, I am a retard and know that if I had an open mind I would probably end up having someone talk me into accepting things which are unacceptable sooner or later. I can't argue for shit, my reasoning is a little wonky. The only way I can protect myself is to close my mind to even listening to things that go against the programming I have in my head right now. To treat anything that challenges my world view with the utmost hostility, and to advocate for the people that push these toxic ideas to be destroyed.