And Abram believed the Lord, and the Lord counted him as righteous because of his faith.

Genesis 15:6

Genesis 12 begins the story of Abram (whose name gets changed to Abraham later) and how God calls him out of his country to go to the land of Canaan telling Abram that he will be made into a great nation (Genesis 12:1-3).

Abram was 75 years old when he left his land and journeyed to Canaan. He traversed the land back and forth to see the land that God would give to him and his descendants (Genesis 13:14-17)

In Chapter 15, Abram stumbles into a problem. For you see, Abram is old now (remember, he left his homeland when he was 75) and Sarai is also old (she’s 10 years younger than Abram which means she was 65 when she left her homeland). Abram and Sarai don’t have a child and Sarai is way past child bearing age.

But God keeps talking about how numerous Abrams descendants would be. (Genesis 12:2, 13:16). Due to age, Abram has already made plans to pass on his stuff to his servant since he has no heir (Genesis 15:2-3). But the Lord reiterates again that Abram will have a son and his offspring will be numerous (Genesis 15:4-5).

Abram, despite being old, and what looks to be impossible, believes God’s promise and that is what made him faithful. He believed that God can do the impossible.

When God promises you something or says that something will happen, claim it with faith.

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.

Hebrews 11:8