Then the LORD God provided a shrub, and it grew up over Jonah, providing shade for his head and saving him from his misery. Jonah was very happy about the shrub. But God provided a worm the next day at dawn, and it attacked the shrub so that it died. Then as the sun rose God provided a dry east wind, and the sun beat down on Jonah’s head so that he became faint. He begged that he might die, saying, “It’s better for me to die than to live.”
God said to Jonah, “Is your anger about the shrub a good thing?”
Jonah said, “Yes, my anger is good—even to the point of death!”
But the LORD said, “You ‘pitied’ the shrub, for which you didn’t work and which you didn’t raise; it grew in a night and perished in a night. Yet for my part, can’t I pity Nineveh, that great city, in which there are more than one hundred twenty thousand people who can’t tell their right hand from their left, and also many animals?” Jonah 4:5-10 (Common English Bible)
God took away Jonah's shade and shelter and again, Jonah became suicidal. What a person focuses on, they will become engrossed by. This is why worship is not an event that we go to or do once or twice a week, but it is a place we live in. Everyone has problems that come at them and challenge them. Everyone has good things, blessings, that bring them joy or comfort. God is above our earthly problems and comforts. Both our problems and our comforts can distract us from God and our lifestyle of worshiping God.
Unbelieving believers delude themselves into thinking that they are saved, God-followers; while they themselves live in unbelief and lack of faith and are not really walking with God, but going their own way. We are all in process and becoming more godly and spiritually mature, until the day we die. But, the unbelieving believer is not in their process. So, God prepares circumstances and even disciplinary action to bring the unbelieving believer into the growth process.
God again questions Jonah about his anger. God does not rebuke Jonah directly or demand change, but is reasoning with him; again. God wants to develop Jonah (1). Again, rather than belittling Jonah, God meets him where he is and compares Jonah's pity for the shrub with his own pity on Nineveh. God does not say, "you are so far from where I am in this, that I can't even talk to you". God steps down into his world and finds an object lesson there. God took away his shade plant and blew away his hut, taking away his comforts that he prized so highly, to get his attention.
There is no final word about Jonah changing. God is who God is: merciful. We learn that in Jonah's book. We also learn that God uses deeply flawed vessels: cracked pots. We also learn that God can change His mind. We saw that some prophecies are conditional: the positive word will come to pass if you walk with God, or the negative word will not come to pass if you repent.
Jesus said, "The citizens of Nineveh will stand up at the judgment with this generation and condemn it as guilty, because they changed their hearts and lives in response to Jonah’s preaching. And look, someone greater than Jonah is here." Matthew 12:41 (Common English Bible)
Jonah, the reluctant preacher-prophet, preached a simple and possibly harsh message to Nineveh for only a few days. He did no miracles. He was a stranger to them. He was prejudiced against his audience. Yet, Nineveh responded beautifully and found God. God had mercy on Jonah all along the way and God was merciful with Nineveh.
The assigner of the assignment is more important than the person who receives the assignment. God can use anyone. Jonah teaches us to heed God's call and let God move. The same mercy is good for the "professional" that is good for the "sinner".