At Mamre Abraham is approached by three visitors: the Lord (Gen. 18:1, 3, 16-17), and two angels (Gen. 19:1); the Lord informs Abraham that Sarah would have a son, even though both of them were advanced in years; Sarah heard the assertion in the tent and she “laughed within herself” (Gen. 18:12).

Her laughter was the laughter of unbelief; consider several thoughts

The Scriptures are emphatic:

Unbelief is the rejection of God’s Word and Rule; it places self at the center rather than God.

For Sarah it was fear and lying; after she laughed, the Lord confronted her about her laughter; Sarah responded: “I did not laugh”; the text adds: “for she was afraid” (v. 15).

Unbelief is never alone in its opposition to God; companion with it are other evils, some of which may not be so obvious.

God confronted Sarah: “No, but you did laugh”; God will not refuse to deal with sin.   God knows our actions, even our inward actions; the text says that Sarah’s laughter was inward, but God knew and confronted her outwardly; sin cannot remain hidden; it must be exposed.

In response to Sarah’s laughter the Lord speaks: “Is anything too hard for the Lord?” (v. 14); the question to Sarah informed her of what she needed to know and the fact that must control her reflection; unbelief is related to an improper perception of who God is; through the question God is redirecting her perspective.

Sarah’s focus was upon herself and her lack of ability; she was thinking too much about herself; the point is that the acute situation a person may be in is not the basis for reflection, but rather God who is in sovereign control of all situations; in a desperate situation the believer needs to hear God say: “I will” (vs. 10, 14).

“The Lord did for Sarah as He had spoken” (Gen. 21:1); she gives birth to a son and Abraham names him Isaac.

After the birth and circumcision, the Scriptures record the words of Sarah: “God has made me laugh” (Gen. 21:6; lit, “made laughter for me”); her laughter had been transformed from doubt to acceptance and joy; she recognized that this was the doing of God: “God has made me laugh.”

Isaac means “laughter” or “he laughs”; thus, the entire family reflects the spiritual journey of the family.

Sarah also stated: “All who hear will laugh with me” (Gen. 21:6); God’s work in a person’s life is not to be harbored but to be shared; other believers rejoice in God’s actions on behalf of any believer; the laughter of one believer is the laughter of all believers.