God promised Abraham a son, though Sarah had been barren for their entire marriage, and both Abraham and Sarah were too old to have children. But, it was a promise of God. Sarah did have initial doubts, but as the text indicates, she “received strength to conceive seed.” Therefore though past the age of childbearing she had Isaac.
Sarah knew that God could and would give her the child. She “judged Him faithful who had promised.” We too need to have faith in both God’s ability and willingness to keep His promises. “Your faithfulness endures to all generations; You established the earth, and it abides” (Psalm 119:90).
The significance of the birth of this child of promise can not be overemphasized. God had a plan. The plan began with Abraham, and was continued through Isaac, his son Jacob, and Jacob’s (Israel’s) sons. A great nation was born out of Isaac’s seed because of the faith of Abraham and Sarah (as good as dead, regarding siring children) as they believed the promise of God.
It is the same with our redemption. It is through Isaac that we are blessed as well. Jesus descended from Abraham, through Isaac.
