Why not question what you are being told instead of following it blindly?
You don't have to do anything.
He is 12. I am sure as he gets older and more informed, both abput his own faith and the alternatives then he will begin to question his beliefs and the justifications behind them, he may decide they still fit in with his worldview, or he may find another interpretation or school of Islam that suits him better...he may find that another relogion or no relogion suits him...
But at only 12, he is still forming those opinion and the very fact that he comes onto and contributes to a forum as diverse as this will only make his education that much broader.