God once again appears to Abram, at 99 years old, and changes Abram's name to Abraham. He changes Sarai's to Sarah. They are both past the natural age for God's promise to be fulfilled. It is now, "God or bust". Once again Abraham responds . . . and that response marked his entire household. . . for all generations to come . . . both in outward performance religion and in those who "dare to live in the risky faith embrace of what God is doing in their lives."
Abraham is still falling into the trap of God+, behavior. Now it is God plus "culturally acceptable" choices. Sarai offers her servant as a "surrugate" mother to give a Abraham the "promised child". The outcomes are far reaching . . . The benefits of waiting for God to fulfill the promise are worth the wait.
Abraham is maturing in the faith God is authoring. You can see it in the story of Lot's rescue. Courage, refusal to take personal benefit from the "power people" involved and generosity expressed, giving the glory to God.
Choosing to Put God and His purposes first in our lives can be challenging and seem counter-intuitive, but the outcome proves to be for our best. Abram faces the challenge of limited resources for living and finds that God makes a way of blessing for him in "barren places".
God started this journey by saying go to a place I will show you, but Abram, made his own calculattions. He chose where he would go when times got tough and how he would remain secure. Tests allow us opportunities to stop relying on our own understanding alone, and enter into God's supernatural strength.
God initiated a journey in Abrams's life. Abraham did what God told Him, but added some of his own destinations along the way. God kept leading Him . . . Discover God's faithfulness to us even when we mess up.