Chapter 3 of Jonah is the place where the fact that the Ninevites worshipped a giant fish comes into play. There are many theories as to why the Ninevites so eagerly took up the call of Jonah and believed him so quickly. Without going into those theories, I believe that one of the Ninevites actually saw Jonah be spat out by the giant fish. For someone to see a giant fish spit a full grown man out on dry land, intact, and for that man to get up off of the ground, start walking and talking, and saying that God was going to destroy the city in forty days... I'm sure that whoever would have seen that would have believed that this man was a messenger sent by Nina. It gave Jonah one heck of a platform to preach from, and it would allow him to educate the listeners on Who God actually is.
The message comes in and spreads like wildfire, like the fire of the Spirit of the Lord. This is the connection to Jonah's name - "dove" - which is symbolic of the Holy Spirit. Reading the first few chapters of Acts will show that the gospel imbued with the Holy Spirit was readily accepted in mass proportions just as Jonah's message was accepted in this chapter. And Jonah's message is much the same as the message that Jesus and John the Baptist brought in chapters 3 & 4 of Matthew (see my post "Repent Ye: For the Kingdom of God is At Hand"). Jonah says, "Yet forty days, and Nineveh shall be overthrown," while the evangelists said, "Repent ye: for the kingdom of God is at hand." Both messages were intended to bring the audience to repentance. It's God's will for all to come to repentance. Peter tells us this in 2 Peter 3:9, stating, "[The Lord] is longsuffering to us-ward, not willing that any should perish, but that all should come to repentance." This chapter in Jonah shows that this repentance was available to everyone, even the enemies of Israel, and that God respected the repentance of all. This is given in more detail and in spiritual imagery as we will see in chapter 4.
What was the sign of their repentance? The outward signs were to fast and to don sackcloth. These are measures to afflict one's self in the flesh. In spiritual imagery, it is to fast from the pleasures of the world, and to humble one's appearance. The inward sign that the king decreed was for everyone to turn from evil and from violence. This is exactly what God wants, as He said to Ezekiel in Ezekiel 18 & 33. It is "fruit meet for repentance", which is to say that it is physical acts that shows that you have changed your life, and that you are humble before God.
Jonah is not happy with God's forgiveness of Nineveh and explains his actions before being swallowed by the fish in the next chapter. God bless.
