The passage (Romans 4:18-22) is one of my favorite Bible verses.

The context is that we are made righteous, not by our deeds, but by faith in God's promises. Paul argues about it from the example of Abraham who believed in God's promise that he will have a numerous descendants when he didn't have any in his old age (Gen 15:6). We too should believe in God's promise of saving grace in Jesus' redemption without any doubt that we are made righteous regardless of our sinfulness.

Abraham's faith teaches me several things:

He believed in the promise against all hope. 18 "Against all hope, Abraham in hope believed and so became the father of many nations, just as it had been said to him, “So shall your offspring be.” Is your situation is totally hopeless? What is God's promise to you right now? Hold onto it.
His faith was not weakened in the deadly situations. 19 "Without weakening in his faith, he faced the fact that his body was as good as dead—since he was about a hundred years old—and that Sarah’s womb was also dead." Are you facing deadly situations? Is your faith weakened? Face them with renewed faith.
Instead of being wavering in unbelief, he was constantly strengthened in his faith. 20 "Yet he did not waver through unbelief regarding the promise of God, but was strengthened in his faith and gave glory to God." How easy is it that you and I are being wavered in our faith when the promise is not accomplished? But Abraham didn't waver as he keeps on focusing on the Lord Amighty. Verse 21 says, "being fully persuaded that God had power to do what he had promised." Verse 20 says that he even gave glory to God. Praise be to the Lord God Almighty, who is our Lord and Father.

Verse 22 tells the result of Abraham's faith: "This is why 'it was credited to him as righteousness.'” We've learned through GCMI GA that we have 'Abrahamic Covenant' (Ge 17:8) in Christ Jesus. Let's see the full blessing of it as we have 'Abrahamic Faith' (Ro 4:18-22). Hallelujah!