The first step is you discredit the Trinity and marginalize believers in it.
eg. It was a late invention by the Romans. It’s illogical, doesn’t make sense. Only radicals really believe it. I don’t see it in MY bible. etc.
Pay attention and see if you don’t see this happening.
My answer to that is that the stupid will fall for anything. God the Father, Jesus the Son and the Holy Spirit all exist together. If the stupid cannot believe this, then I cannot stop them, just like I cannot stop the Democrats from being the evil, blind liberals that they are.
Since the night Obama won the election I pretty much worry only about the family members that sit at my kitchen table, because those are the mouths I have to feed and the ones I can pray for. I’m their mother. I have to shut out the rest, for my own sanity a lot of the time.