God tells Moses, “I am the God of Abraham, the God of Isaac, and the God of Jacob” (Ex. 3:6); Jesus quotes this verse against the Sadducees to prove the Resurrection: “He is not God of the dead, but of the living” (Mark 12:27).
How does this prove the Resurrection? Because this phrase is spoken by the Great I AM (Ex. 3:14), who is life; when this God of life and existence enters into a covenant of faithfulness with a person or people (Father Abraham and his many sons…), they will by definition be a people who are alive. He is God of the living. Obviously, this demonstrates, as Jesus shows, the Resurrection.
But I also think it implies regenerate church membership, or the doctrine that the church is made up of only those who are truly born again. Baptists not only believe this, they practice it (at least in theory). They admit to church membership only those who have been born again, converted, regenerated, given new life. Those who have been given new life by God then follow Jesus in baptism. They are baptized because they are alive. Baptism draws a picture of dying with Christ to sin and self (going under the water) and being raised with Christ to a new life of authentic worship (coming up out of the water). Baptism shouts in a picture: “He is the God of Abraham, Isaac, and Jacob. He is not God of the dead, but of the living!”
So, in a way, Moses, when he believed in “the God of Abraham, Isaac, and Jacob,” proved that he was a Baptist.