1:7 - Each man said to his mate, “Come, let us cast lots so we may learn on whose account this calamity has struck us.” So they cast lots and the lot fell on Jonah.
Casting lots was a common way to determine the will of the gods or even in Israel's case, the will of God There are many instances of Israel casting lots in the Old Testament; see specific examples in Lev. 16:8-10, Num. 26:55, and Joshua 7:14-18. The last reference in Joshua provides an example of how the sailors were using the lot; God commands Joshua to use the lot to determine who the offender is. Jonah would not only have been familiar with this process but would also be familiar with Prov. 16:33 The lot is cast into the lap, But its every decision is from the Lord.
1:8 - Then they said to him, “Tell us, now! On whose account has this calamity struck us? What is your occupation? And where do you come from? What is your country? From what people are you?”
Here is the next stage of the Lord's discipline in Jonah's life. After the general call to repentance (the storm) and the confrontation by one (the captain), God brings the confrontation by many (the sailors).
Notice, nobody, even Jonah in the next verse, disputes the outcome of the lot. It is accepted as the truth of the gods, in the sailors' view, and the truth of God, in Jonah's view. Of course, Jonah knew he was the cause anyways...
The sailor's questions were designed to ferret out which god was causing the storm so that they could try to appease it. Remember, gods were thought to be regional at this point in time, so figuring out which part of the world and of what people Jonah belonged to was key in the sailors' minds.
1:9 - He said to them, “I am a Hebrew, and I fear the Lord God of heaven who made the sea and the dry land.”
Jonah reveals more of his heart in this statement. Instead of humbling himself in repentance at the sailors' questions, he arrogantly states his people and his God.
An interesting side note: Jonah states that he fears the LORD God of heaven, and yet he will not do His will. This is the exact attitude of the northern kingdom; they feared the LORD and would not do His will.
John MacArthur notes that Jonah's description of the Lord may have been selected to emphasize God's sovereignty over any of the gods that the sailors worshipped and would have struck fear into the crew. No wonder they respond how they do in the next verse.
The pressure is building on Jonah to repent. God is in the third stage of discipline and there is only one thing left after the confrontation by many. Jonah continues to be stiff necked and arrogant in his running away; he refuses to repent even at the expense of losing not only his own life but also all the sailors' lives. Jonah shows his hard heart throughout the process of God's discipline.
The original audience would still be on Jonah's side at this point. They would see no need to answer the Gentile sailors beyond what Jonah stated and would certainly see no need for repentance.