7:1 And the high priest said, “Are these things so?” 2 And Stephen said:
“Brothers and fathers, hear me. The God of glory appeared to our father Abraham when he was in Mesopotamia, before he lived in Haran, 3 and said to him, ‘Go out from your land and from your kindred and go into the land that I will show you.’ 4 Then he went out from the land of the Chaldeans and lived in Haran. And after his father died, God removed him from there into this land in which you are now living. 5 Yet he gave him no inheritance in it, not even a foot's length, but promised to give it to him as a possession and to his offspring after him, though he had no child. 6 And God spoke to this effect—that his offspring would be sojourners in a land belonging to others, who would enslave them and afflict them four hundred years. 7 ‘But I will judge the nation that they serve,’ said God, ‘and after that they shall come out and worship me in this place.’ 8 And he gave him the covenant of circumcision. And so Abraham became the father of Isaac, and circumcised him on the eighth day, and Isaac became the father of Jacob, and Jacob of the twelve patriarchs. (Acts 7:1-8 (ESV)
Stephen begins to explain his beliefs and he starts with Abraham. He starts with the Old Testament. Of course he is speaking to Jews who know the Old Testament even if they don’t understand it. Now he will give them an interpretation of it that centers in Christ, in whom the Old Testament finds fulfillment. It is essential to do this. But throughout his recounting of the Old Testament he will emphasize just how improbable the faith of Abraham has been, how it has always been misunderstood, and that God’s people have always been a persecuted minority with in Israel, and the majority of Israel have always been unbelievers. Jesus Christ himself had rubbed this in the face of his hometown crowd when he spoke of the many widows to be found in the days of Elijah, and many lepers in the days of Elisha, yet it was a gentile widow who housed Elijah and found relief from God during the drought, it was Namaan a gentile general and raider of Israel that was healed. (Luke 4)
God called Abraham and told Abraham what was going to happen to his people. Four hundred years they would be enslaved, but in the end God would judge the nation that enslaved them. So it always is with God’s people, they are persecuted, but they know that what they endure is not for naught. In the end God will deliver them, their persecutors will be judged. Stephen understands that this history is replaying itself now as the new Israel, the church is born.