The friends of God are those who trust the promises and testimony of God and want to communicate with God face to face, despite knowing how disastrous that could be for one’s casual observance of God. We can know God as one speaks to a friend, but once God calls you to be His friend, you life will never be the same.
The primary lesson of the book of Jonah is this: God is willing to hear to remove sin, even for people you don’t like. God doesn’t want to kill anyone: Christian, Jewish, Hindu, Muslim, Buddhist, whatever. God wants all these groups to be saved. When Yeshua (Jesus) said that the sign of His being the Messiah was the “sign of Jonah” (Matt. 12:39; 16:4; Luke 11:29), it was not only about the three days in the fish representing his three days in the grave. The entire book of Jonah is the “sign of Jonah” Yeshua references.
Jonah 3 is a short chapter, but there is a lot in there. We are shown how the individual Ninevites responded to the message of Jonah. The repentance of the people grabbed the attention of the king of Nineveh who encouraged their repentance. The people of Nineveh believed God, and “it was credited to them as righteousness” (cf. Gen. 15:6), just as it was for Abraham.
These seemingly randomly inserted passages do fit the previous theme of learning to see people how God sees them: Few rich people in heaven, a camel through the eye of a needle, a warning about the restoration of Yeshua three days after humiliation and suffering, healing of a blind man, repentance of Zakkai (Zaccheus) the tax collector, parable of 10 coins for servants of a king.
Those baptized by the Messiah’s messenger, Yokhanan (John), and the woman who washed Yeshua’s feet understood repentance — turning back from a life in rebellion against God — and forgiveness — God’s removing the stain of guilt on a person for that rebellion — better than the those supposed to be in charge of teaching Israel about God.
The phrase similar to “baptism for repentance for forgiveness of sin” is repeated several times in the Gospels and by Peter in the temple on Shavu’ot (Pentecost). This is not a “warm and fuzzy” message we receive from Yokhanan (John the Baptist). However this isn’t God’s way of finding people inconvenient but a call to true repentance and to become true sons of God.
After the prophet Natan (Nathan) confronted David over his adultery with bat-Sheba (Bathsheba) and murder of her husband, Uriah, David expresses true repentance — revealed in Psalm 51 — and is granted mercy.