After that Abraham had come back from beating the four kings and bringing Lot and his family back and after having met Melchizedek and the Sodom king, God and Abraham had a conversation about the future, an important and interesting talk.
This was a time of war, Abraham had just killed a lot of people from the east, soldiers of the four kings of Mesopotamia land, he had killed a lot of fathers and sons and could expect vengeance from their families, but also he had gained a lot of respect in the land of Canaan and in the valley of Jordan. Abraham was loved and hated.
Then God met him and the first thing He said to Abraham was; “Do not be afraid, Abram, I am your shield; Your reward shall be very great.” Humanly speaking this was a time for uncertainty and fear for Abraham, but God made it clear to him that He was stronger and greater than any of his enemies and would protect him and his family, like God did in Egypt.
What happened next was that Abraham believed God; he had experienced God for a long time and this together with the closeness to God resulted in faith. God saw that Abraham believed in his heart and that made Abraham righteous, he was credited the righteousness of Jesus.
What made Abraham believe God in these times of fear and war, the reason is all the words from the mouth of God that Abraham had heard and collected in his heart. The faith comes from hearing. If what you hear comes from the world and medics your faith will be in the world and in the medics, but hearing the word of God will result in believing God.
Sarah could not have children; But God took Abraham outside his tent and told him that his descendants would be as numerous as the stars in the sky. Abraham believed in God’s greatness, but still he did not believe this in his head, his thinking was based on the fact that Sarah could not have children and he said to God shall this Eliezer from Damascus inherit all that I have.
Abraham believed that God had a plan, but what was it, did God mean that he should take another wife that could give him children? God just said that this Eliezer should not inherit him and left it there for Abraham to believe in his good and reliable friend God, YAHAWAH.