What does Hebrews 11:19 mean?
Faith, in a biblical sense, is not blind. It is based on prior experience, and means trusting that God can work in ways we cannot immediately see (Hebrews 1:1–3). The ultimate example of this type of faith is Abraham's obedience to God, when commanded to sacrifice his son, Isaac (Genesis 22:1–14). This was the same son through whom God had sworn to fulfill His promises to Abraham (Hebrews 11:18; Genesis 21:12). In literal terms, this command would seem to be a violation of God's nature, as well as a break in His agreement with Abraham.And yet, Abraham had seen God provide him with a son despite doubts and delays (Genesis 17:17; 21:5). Abraham had seen God rescue Lot (Genesis 19:15–16), despite Abraham's fears about the judgment of Sodom (Genesis 18:22–23). So, when God gave His mysterious command, Abraham was willing to trust in God and obey—proving by his actions that he possessed a true, godly faith (James 2:14–17). For this reason, he was not only rewarded by God (Genesis 22:15–18), who never intended to let Isaac die (Genesis 22:12), but he became an example of faith for the rest of humanity.
Here, the writer of Hebrews offers one of the justifications Abraham would have held as part of his faith in God. At the time Abraham spoke with God, Scripture had not recorded any instances of God bringing someone back from the dead. And yet, Abraham's faith in God's assurances was strong enough that he felt God could resurrect Isaac, if need be. Poetically speaking, God did "bring back" Isaac from death, by sparing him after Abraham had committed to follow through with the sacrifice.