What does Hebrews 11:20 mean?

In this passage, the writer of Hebrews continues to demonstrate that godly faith is trust, not merely agreement. We demonstrate faith in God when we rely on Him to keep His word, even when we cannot see or understand all of the details (Hebrews 11:1–3). Earlier, examples were given of faith in the face of general doubts, such as Noah (Hebrews 11:7) and Sarah (Hebrews 11:11). Now, the emphasis is on those who faced more immediate, personal moments of testing. The ultimate example of this is Abraham (Hebrews 11:17–19), who exemplified trust in God through his obedience regarding his son, Isaac (Genesis 22:1–14).

A key point being made is that many of the promises given by God have an eternal perspective (Hebrews 11:10). Not all of the figures mentioned in this chapter saw those promises come to full fruition in their earthly lives (Hebrews 11:13). And yet, those very promises were fulfilled, on earth, through their descendants. Others will be fulfilled in the future, as God completes His plans. This is part of the point of their faith: recognizing that their earthly lives were not the end of God's ability to fulfill His purposes.

Following this pattern, Isaac received the promises God had given to Abraham (Genesis 21:12), and passed them along to his children. Despite not seeing how or when they would come true, and dealing with considerable family strife (Genesis 27:1–40), Isaac exhibited faith and obeyed God, though he was extremely old and had not seen a total fulfillment of the divine plan.