Verses 3-4 reminds me of a sermon I preached on May 30th 2010: Peace with God. It is about the exercise aspect of the Gospel: Kids practicing their endurance and a friend of mine getting ready for the Iron Man.
Verse 16 stresses that we are saved without deserving it: We are not able to earn, add or take away from salvation. It is freely given. Good news!
Verse 20 has a logic that has blown great minds: The bigger our sin the bigger God’s grace. Martin Luther is known for his down-to-earth quotes. Here are some very good one based on our verse:
“A happy fart never comes from a miserable ass.”(Uncommon Travel Germany)
“You did not burp, you did not fart, didn’t you like the meal.”(Guardian)
“Sin boldly!” (WikiQuote)