It had been 23 years since God first promised Abram that he would bless him and make from him a great nation (Gen 12:1-3). That is a long time to wait for a promise to come to pass. Yet, during that time Abram’s faith didn’t weaken or waiver (Rom 4:19-21).

During all this time, there is 13 years of domestic tension via Hagar and the birth of Ishmael. The distress of Abram and Sarai’s attempted shortcut to obtain God’s blessing is the background against which Gen 17 is set. It seems that Moses intends us to understand that these 13 years have been filled with domestic tension – and you can understand why. There have been years of waiting on a promised child, and Abram and Sarai’s way of “helping” God has turned out poorly.

But now God comes to Abram, and you might expect God to reveal his anger at Abram and Sarai for their continual struggles and failures, but not so. God comes to Abram and elevates his faith by confirming the promise with the covenant with a sign -- circumcision.

Signs have always been a way that God helps his people express faith, and God requires them. Jesus, describing the New Covenant -- in which he dies for our sins -- gives the disciples the sign of the Lord's Supper (Matt 28:26-29; Mark 14:22-25; Luke 22:14-20; cf. John 6:47-53).

If Abram refused the sign of the covenant, he would have been cut off from God's family. It was the same as rejecting God (Gen 17:14). In the New Covenant, Jesus fulfills all the promises of the Old Covenant, and before he was crucified gave the Lord's Supper as the sign of the New Covenant for all those who believe in him. And it is no different, those who refuse this sign are cut off from God (John 6:47-53).

God’s signs are not the way we are saved, but they expressions of saving faith. This all started with Abram in Genesis 17.