"Moses said, 'The Lord God shall raise up for you a prophet like me from your brethren; to Him you shall give heed in everything he says to you.  And it shall be that every soul that does not heed that prophet shall be utterly destroyed from among the people.'  And likewise, all the prophets who have spoken, from Samuel and his successors onward, also announced these days.  It is you who are the sons of the prophets, and of the covenant which God made with your fathers, saying to Abraham, 'And in your seed all the families of the earth shall be blessed.'  For you first, God raised up His servant, and sent Him to bless you by turning every one of you from your wicked ways."

In Genesis, God made a covenant with Abraham.  Peter is telling the people of Israel how this covenant has been fulfilled in the person of Jesus Christ.

God told of a blessing that would happen through Abraham's seed.  That men and women, families throughout the world would see God and His blessings because of the obedience of one man - Abraham. 

Jesus Christ is the completion of that blessing.  Even today, all families throughout the world are blessed because of Abraham's Descendant.  This is why the gospels are so good about defining Jesus' connection to Abraham.

But Peter goes one step further in his discourse to the people.  He also tells them that they are still bound to the blessings of that original covenant.  This is why they were turned from their wicked ways.  They are still responsible for blessing the world.

And so are we.  Any who call ourselves heirs with Christ Jesus.  We have the privilege of seeing God work through Christ in us.