Bucholz-You could ask your little brother questions that come from the Bible Stories book, such as 'Why do you think Jehovah let Aaron make a golden calf to worship and he didn't get punished, but the man who was picking up wood on the Sabbath Day stoned to death?' 'Which do you think was the worse sin, leading a whole bunch of people astray from worshipping God, or trying to make a fire to cook your food?'
Use critical thinking questions and reasoning, let him work the answers out for himself though, so your mom can't say that you've been telling him apostate things.