Everything depends on having faith in God, so that God's promise is assured by his gift of undeserved grace. 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.
Suppose someone disagrees and says, “It is possible to have faith without doing kind deeds.” I would answer, “Prove that you have faith without doing kind deeds, and I will prove that I have faith by doing them.”
Stephen answered: Friends, listen to me. Our glorious God appeared to our ancestor Abraham while he was still in Mesopotamia, before he had moved to Haran.
But I brought Abraham across the Euphrates River and led him through the land of Canaan. I blessed him by giving him Isaac, the first in a line of many descendants.
Abraham had been promised that Isaac, his only son, would continue his family. But when Abraham was tested, he had faith and was willing to sacrifice Isaac,