Well over a decade has passed since Abram had been “reckoned righteous” due simply to his faith. The intervening time has seen him trying to accomplish God’s promises in his own strength. It has led to a lot of damaged relationships and strife. And it appears to have distanced him from God for a while. In any rate, we are not told that God spoke to him during this time.
It is important to note that the Bible tells us he was justified in God’s eyes back in chapter 15. It is Abram’s faith that saves him. And, while obedience is an outward sign of faith, getting things exactly right is not. It is possible to turn to God in faith and still be mistaken about exactly how salvation is accomplished and what the Christian life looks like.
That said, when we truly trust God and want to follow Him, He will set us right. God finally appears to Abram again and reaffirms His covenant promises. He gives Abram a new name. He will now be Abraham. He goes from being “great father” (what an embarrassing joke of a name that must have been!) to “father of many” (an even more unlikely one). And this time, God tells Abraham what He expects of him in this relationship. Abraham is to live as God desires.
Again, this is not a condition of the relationship; it is the desired result. Abraham is God’s child so (and not because) he is expected to live according to God’s desires. And mere circumcision is not the extent of that behavior. It is just the sign, the reminder. God’s people are set apart from the world symbolically, but the signs require an authentic life of holiness to mean something. And, the authentic life requires real trust, real faith. Signs without obedience are hollow. “Obedience” without trust are hypocritical.
Abraham will continue to make mistakes. But they will diminish as he grows in faith. And it is God who keeps the promise; God keeps the relationship.