I often think of Romans 4:17 which says, “…God…calls those things which do not exist as though they did.” His promises to Abram were for the future. Sarai was at that time still barren. Our lack does not affect God’s promise in any way.
Genesis 17:1 says, “When Abram was ninety-nine years old, the Lord appeared to Abram…” Verse 4 says, “…you shall be a father of many nations.” According to the promise God changed his name to Abraham. 24 years had passed. God also changed Sarai to Sarah.
God next required that all the males from 8 days old would be circumcised (verses 10-13). As I read this, I realized that the circumcision had to take place before God’s promise to him could be fulfilled.
My mind immediately went to Colossians 2:11. It says, “In Him you were also circumcised with the circumcision made without hands, by putting off the body of the sins of the flesh, by the circumcision of Christ.”
Speaking of our salvation, Romans 6:6 says, “Knowing this, that our old man was crucified with Him that the body of sin might be done away with, that we should no longer be slaves of sin.”
In Genesis 18 Abram was visited by three men. He immediately offered them hospitality. In verse 10 the Lord spoke another promise, “…I will certainly return to you according to the time of life…Sarah your wife shall have a son…” Sarah heard Him and laughed. Verse 14 says, “Is anything too hard for the Lord?…”
Even with these promises stacked up in Abraham’s heart, he again reacted in self-preservation. He told Abimelech, the king of Gerar, in Genesis 20:11 that he had lied about his wife being his sister because, “…they will kill me on account of my wife.”
God’s set time had come. The promise was about to be fulfilled. Genesis 21:1-2 says, “And the Lord visited Sarah as He had said, and the Lord did for Sarah as He had spoken. For Sarah conceived and bore Abraham a son in his old age, at the SET TIME of which God had spoken to him.”