Pull him out of the school or church that perverted his mind. I am dead serious.
Where is he getting the propaganda from? So sorry to hear this. Obviously, you will have to ask him for more info.
Might have to go to court down the road. Keep a log of what your child says and put the date and time. If the child had recently returned home from the mother make a note of that as well. Some day you might have to use this log to validate your concerns before a judge. Lawfag so I know what I am speaking of.