What does Hebrews 11:18 mean?

This passage in Hebrews demonstrates that godly faith is exemplified by trust. When we cannot see the future, "faith" is our ability to trust in God that He will make good on His promises (Hebrews 11:1). This is the kind of faith which God honors (Hebrews 11:2), since it means we are confident in God's ability to work in ways we cannot see (Hebrews 11:3). Prior examples included those who faced general doubt, but persevered, such as Noah (Hebrews 11:7). The current example is one of an immediate, dire moment of decision: God's command for Abraham to sacrifice his son, Isaac (Genesis 22:1–14). In hindsight, we know that God did not allow Isaac to die, and provided a substitute at the last moment. But when the command was given, Abraham did not have that perspective.

As this verse reminds us, Abraham had been given promises by God (Genesis 17:3–8), and those promises were explicitly tied to the life of Isaac (Genesis 17:18–19). The writer cites Genesis 21:12, where God clearly states that it is Isaac who will carry on Abraham's legacy. And yet, this is the son God commanded Abraham to sacrifice. Abraham would have been mystified, wondering why God would ask such a thing, and how God would fulfill His promises.

And yet, Abraham had learned that God was able to work in ways Abraham could not see. God had given him a son when he was 100 years old (Genesis 17:17; 21:5), and saved his nephew Lot from the judgment of Sodom (Genesis 18:22–23; 19:15–16), all despite Abraham's lack of understanding. This is the basis for Abraham's faith, and that faith was the basis for his obedience to God. The passage will continue by offering one possible explanation of Abraham's willingness to obey.