Well. LOL!!! If our church did something similar (which they wouldn't), we would be having a meeting with the pastor immediately to address it. WAY out of line.
And "which positions are biblical?" I didn't know the Bible discussed that.
However...(and I know you believe your son), its always a good idea to ask a few adults about it, and get their take on the events before you go for the jugular. Children can misunderstand, or mistake one thing for another. I'm not saying he did...but its best to
have your ducks in a row and have indisputable facts before you go into attack mode.
(I would go so far as to ask in a
very friendly and non-confrontational tone..."Hey, my son told me you guys taught a biblically based sex ed curriculum last year--is there any way for me to get a copy of that?"
Anyway, if the facts are accurate as your son has presented them, there would be a very serious meeting with the pastor about the Sunday School department. (or youth dept.)
Sometimes things are done without pastoral approval, so you can't assume the pastor knew or approved. But if he did....tsk tsk tsk.
Like I said--make sure you get the facts first from several reliable sources, and if you had a copy of the curriculum in hand (assuming there was any), it will be much better.
I had to educate Hannah on specifics a couple of years earlier than I had planned because her cousin gave her misinformation--such terrible misinformation, that leaving her with that info would have been more traumatic than setting it straight in great detail. I was NOT happy about it.
And when I was done, I called my sister up and told her she needed to inform HER daughter of the birds and bees, since obviously my niece didn't have a CLUE...LOL!