Summary: How God had prepared Abraham for the birth of Isaac.
“The Birth of A Promise”
It took God twenty-five years to shape that man to whom He could entrust Isaac. After twenty-five years, in the fullness of God’s time, God gave Abraham and Sarah the promised son. God is never late!!
I. THE COMPLETION OF A OF A PROMISE
“And the LORD visited Sarah as He had said, and the LORD did for Sarah as He had spoken. (2) For Sarah conceived and bore Abraham a son in his old age, at the set time of which God had spoken to him. (3) And Abraham called the name of his son who was born to him—whom Sarah bore to him—Isaac. (4) Then Abraham circumcised his son Isaac when he was eight days old, as God had commanded him. (5) Now Abraham was one hundred years old when his son Isaac was born to him. (6) And Sarah said, “God has made me laugh, and all who hear will laugh with me.” (7) She also said, “Who would have said to Abraham that Sarah would nurse children? For I have borne him a son in his old age.”
This miracle would be the source of joyful reflection and discussion for years to come. Sarah and Abraham name their son, Isaac, which means laughter. At first Sarah laughed in derision at the suggestion that she would give birth to a son, after the normal years of childbearing are so far gone. But now she says, “God has made me laugh, and all who hear will laugh with me.” She is laughing in joy at the fulfillment of God’s promise. Laughing in joy because of the goodness of God.
The joy that Sarah experienced is really the kind of joy that you and I as Christians should also be experiencing. Tony Campolo expresses it well when he writes, “Joy in Christ requires a commitment to working at the Christian lifestyle. Salvation comes as a gif, but the joy of salvation demands disciplined action. Most Christians I know have just enough of the Gospel to make them miserable, but not enough to make them joyful. They know enough about the biblical message to keep them form doing the things which the world tempts them to do; but they do not have enough of a commitment to God to do those things through which they might experience the fullness of his joy.” (Tony Campolo. Seven Deadly Sins. p. 21)
Sarah’s reason for this joyful laughter is not just the birth of her son, but joy at all that she has learned about God. Let’s examine the lessons to be learned from it.
A. SHE LEARNED THAT GOD IS ALWAYS FAITHFUL TO
Three phrases in verses one and two, “as He had said,” “as He had spoken,” and and “which God had spoken” pinpoint the theme of promise and fulfillment. God had performed that which He had promised. Three times the passage points out that these things happened as the Lord has promised.
B. SHE LEARNED THAT GOD IS SO POWERFUL THAT
NOTHING IS TOO HARD FOR HIM.
You will remember that when Sarah was told in Genesis 18 (quickview)  that she was to bear a son, she responded with laughter. The angelic visitor responded to Sarah’s laughter with the question, “Is there anything to hard for God?” (v. 14). “Too hard” means not only too difficult but also too extraordinary or too marvelous.