What does Romans 4:22 mean?

Paul has described Abraham's amazing faith. God had promised to give Abraham a son with Sarah, and to make Abraham the father of many nations. Then the clock started. The years passed. Abraham did some good things, and he made some mistakes. He stood for what was right, and he sinned. Time went on and on, and no baby arrived. Even though Abraham was elderly when first called by God (Genesis 12:1–4), he had to wait another 25 years to see the promise completed!

Through all of this, Paul has written, Abraham's faith in God did not waver. In fact, Abraham's faith grew stronger, and he continued to give glory to God (Romans 4:20). He continued to be fully convinced that God was able to keep His promise (Romans 4:21), even as he watched his body age and lose function until he was 100 years old and "as good as dead" (Romans 4:19).

Now Paul quotes Genesis 15:6 once more, exclaiming that this was why Abraham's faith was counted to him by God as righteousness. Abraham believed God. God received his faith and declared him justified. Paul will show in the following verses that the same can happen for us when the focus of our faith is on what God did for us through Christ.