I still find this very hard to believe. I also question their heart. As they don't change their position when the truth is in their face. I also have learned the devil will mix lies with the truth...to discredit the truth. Or have a "crazy person" endorse something to discredit it. I see it in this.
Someone here once said you can't be persuaded or convinced to believe two times two is five, or something like that. There isn't any place for convincing, not when you know 2 + 2 = 4
You might under duress testify falsely that 2 + 2 = 5, but only under duress. And if you're under constant duress to constantly testify and confess and agree to 2 + 2 = 5, I could see that messing with your mind. That could be brainwashing. But what do you do if you're brainwashed but don't know it? There's got to be objective, trustworthy ways to tell. So that you can tell. Like, "I am brainwashed," how can you tell? when you're in the middle of brainwashing? You can't, that's what brainwashing is.
You're right about the Devil. And he does impose duress on us, as much as he can, because he hates you passionately.