God’s promise to Abraham and Sarah is a covenant. God does not only share His intentions to save the world but acts on them. A promise from God is as sure as done. God’s ability to declare and sustain covenants is a particular way God reveals Himself and His mission to us so we can understand it and participate in it. Our faith is trusting the promises God has made. Look again at the Abrahamic Covenant (Genesis 12 & 15). See how God intends to use His people to accomplish His purposes? God does not save us to extract us from the world, but to send us out to bless the world in His name.