‘And who is he who will harm you, if you are zealous for what is good?'
The first principle is that if they are zealous for what is good (i.e. what has already been revealed as good in the previous verses), then no one will justly harm them. In the normal course of events they will be safe from harm. They can then be sure that if they do suffer it will not be because of their own deserts but within God's special purposes.