Then you will be acting like your Father in heaven. He makes the sun rise on both good and bad people. And he sends rain for the ones who do right and for the ones who do wrong.
Everything depends on having faith in God, so that God's promise is assured by his great kindness. This promise isn't only for Abraham's descendants who have the Law. It is for all who are Abraham's descendants because they have faith, just as he did. Abraham is the ancestor of us all.