Read Mark 8:31-38 with your family.
Sometimes we have friends who support us in everything we do without a problem. Sometimes we have friends who support us even if they think we are making a bad choice.
And sometimes we have friends who try to talk us out of things because they are afraid we will get hurt.
In this story before Jesus and his followers get to Jerusalem, Peter was trying to talk Jesus out of doing things that would hurt and probably kill him. The language Jesus used “Get behind me, Satan”, sounds really harsh, but what it really meant was “stop tempting me”.
Jesus knew what he had to do, and he knew that the people in Jerusalem would be angry once he was finished. So Jesus needed all his strength and the support of his friends to do the job. Anyone who questioned what Jesus was going to do was just too hard for Jesus to deal with.
Jesus was never angry at Peter, he just needed Peter to understand how hard it was already, and Jesus simply could not hear the thought of doing something differently.