I’ve noticed how those who subscribe to cults, parrot the talking points of their teachers. There seems to be a trend in labeling believers who doctrinally understand the Trinity, as being “Brainwashed”. I wonder which cult leaders routinely use that label.
Check this out. Loads to choose from. I noticed one group on the list discouraged followers from engaging in logical debate, to use prepared answers and when challenged tell people they are liars. Sounds familiar.
http://www.spiritual-research-network.com/f/falseviewsofjesus_compilationlist.pdf
It’s probably just his own favorite way of denigrating christians. There’s plenty of non-trinitarians who are not involved with cults.