Gen 18:9 And they said unto him, Where is Sarah thy wife? And he said, Behold, in the tent.
Gen 18:10 And he said, I will certainly return unto thee according to the time of life; and, lo, Sarah thy wife shall have a son. And Sarah heard it in the tent door, which was behind him.
Gen 18:11 Now Abraham and Sarah were old and well stricken in age; and it ceased to be with Sarah after the manner of women.
Gen 18:12 Therefore Sarah laughed within herself, saying, After I am waxed old shall I have pleasure, my lord being old also?
Gen 18:13 And the LORD said unto Abraham, Wherefore did Sarah laugh, saying, Shall I of a surety bear a child, which am old?
Gen 18:14 Is any thing too hard for the LORD? At the time appointed I will return unto thee, according to the time of life, and Sarah shall have a son.
Gen 18:15 Then Sarah denied, saying, I laughed not; for she was afraid. And he said, Nay; but thou didst laugh.
Sarah laughed at the idea that she would give birth to a baby. This was a natural response for a woman of ninety, well past child bearing years. We probably would have laughed at the idea too. But these were angel messengers speaking from God. She knew the limitations of the natural world, but the messenger reminded her "Is anything too hard for God". A person of God wants to believe God and obey him, but too often we think with our natural minds, wanting to reason, to question what we hear.
Sarah knew the promise of God that through Abraham would come a son and he would have a multitude of descendents. She knew and in her impatience gave her handmaid, Hagar to Abraham to make a child. The son born was Ishmael. But he was born of the will of the flesh using the natural mind. There was yet a son to be born from Sarah, the miracle child from God, by faith, Isaac, meaning laughter.
Let us not put our natural minds in the way of God's miracles. Do you think you are too old to serve God? Obey by faith and see the grace of God in your life. A final thought; do not serve God in the flesh, substituting stories and jokes for the word of God. We are called to preach the word of God, not to be entertainers. We may be able to make an audience laugh in church, spending most the time making up stories from our natural mind, but is God laughing?
Gal 4:22 For it is written, that Abraham had two sons, the one by a bondmaid, the other by a freewoman.
Gal 4:23 But he who was of the bondwoman was born after the flesh; but he of the freewoman was by promise.