Abram was ten years past what we would call retirement when he was called to leave Haran and go to another land. He sold up and left. His family and nation was left behind, for he trusted in the promises of God.
This faith, ridiculous faith, for Sarai would have been beyond childbearing at that time, was what God accounted as righteousness. For no one can meet God's standards of probity.
Which is why we should trust him.
12 Now the Lord said to Abram, “Go from your country and your kindred and your father's house to the land that I will show you. 2 And I will make of you a great nation, and I will bless you and make your name great, so that you will be a blessing. 3 I will bless those who bless you, and him who dishonours you I will curse, and in you all the families of the earth shall be blessed.”
4 So Abram went, as the Lord had told him, and Lot went with him. Abram was seventy-five years old when he departed from Haran. 5 And Abram took Sarai his wife, and Lot his brother's son, and all their possessions that they had gathered, and the people that they had acquired in Haran, and they set out to go to the land of Canaan. When they came to the land of Canaan, 6 Abram passed through the land to the place at Shechem, to the oak of Moreh. At that time the Canaanites were in the land. 7 Then the Lord appeared to Abram and said, “To your offspring I will give this land.” So he built there an altar to the Lord, who had appeared to him.
8 By faith Abraham obeyed when he was called to go out to a place that he was to receive as an inheritance. And he went out, not knowing where he was going. 9 By faith he went to live in the land of promise, as in a foreign land, living in tents with Isaac and Jacob, heirs with him of the same promise. 10 For he was looking forward to the city that has foundations, whose designer and builder is God. 11 By faith Sarah herself received power to conceive, even when she was past the age, since she considered him faithful who had promised. 12 Therefore from one man, and him as good as dead, were born descendants as many as the stars of heaven and as many as the innumerable grains of sand by the seashore.
All the nations who have followed the gospel are accounted within this lineage of faith. it is not the physical, but the covenantal relationship. Do not forget that Abram had a son called Ishmael, by an Egyptian concubine.
We are chosen by God, to be a people of faith.