My little grandson has religion every day at assembly, before school starts. “Mummy”, he said to his mother, “do you know , there are actually people in the world who don’t believe in God?” It’s o.k. He will hear nothing negative from me. I will only tell him to use his mind and think for himself. He will get a good and a real education in any case. The outcome is for him.
Your grandson is lucky. He has the privilege of hearing two sides of a question and being able to make up his own mind. Too many people in this world are conditioned by propaganda from birth and are surrounded with lazy minded conformists who reinforce the propaganda.