The laughter of unbelief ... and the laughter of faith
There are two very different kinds of laughter in the story of Sarah. there is the laughing in Genesis 18:13-15. This is the laughter of unbelief, laughing at the Lord, with the proud attitude that God's Word cannot be taken seriously. There is the laughter of faith, the laughter which rejoices in the Lord - "God has brought me laughter and everyone who hears about me will laugh with me" (Genesis 21:6). This is the rejoicing of Sarah at the birth of Isaac. Hagar and Ishmael are not forgotten - God's sun shines on the righteous and the unrighteous (Matthew 5:45). The final section - Genesis 21:22-34 - sees Abraham acting more nobly than he did in Genesis 21. It ends with Abraham worshipping the Lord, the everlasting God (Genesis 21:33).