and said "Mummy, did you know that Muslims have to wash before they pray to their false God?"
I did the softly-softly approach about people having different names for essentially the same god, and that there was no single "right" god only what was the right god for each individual person. But he was adamant that only God, Jesus' father, is God and everything else is false and wrong. So then got very stern and gave him a bollocking about all religions being equally valid and how wrong and rude it is to call something false when someone who believes in it might hear you and be upset.
I know that he didn't get this from his teachers, and he says that a particular boy was teaching everyone to say this. It is a Christian school, but they are very open and welcoming towards other religions. Do you think I should send a note to his teacher to let her know what he's been saying so that she can keep an eye on him (and the others) or just let it go? He's in yr 1 (someone is bound to ask).