In Jonah 2:1-10, Jonah is trapped in the belly of the great fish. He prays for salvation, and in the end, after this terrible trial, he is vomited forth onto dry land.

Before a new church -- either a state of good and truth with a group of people, or a new state of good an truth in ourselves - can come into existence, a period of temptation, of struggle, must occur. During this time a remnant of good and truth from prior states, will be preserved. This happens to us. When we really don't want to do something that we know we should do, we get into a state of spiritual temptation. That's what this chapter is about.

In Arcana Coelestia 756, it says: "In Jonah, 'The waters closed around me, even to my soul, the deep surrounded me. Here... 'the waters' and 'the deep' stand for the full extent of temptation.

This chapter also prophesies, or foreshadows, the combats that Jesus Christ would have with the hells, and his most grievous temptations at the time. The “three days and nights during which Jonah was in the bowels of the fish,” signify the entire duration of the combat with the hells.

In the New Testament, in Matthew 12:39-41, there's a reference back to this story:

"No sign will be given to it except the sign of the prophet Jonah. For as Jonah was three days and three nights in the belly of the great fish, so will the Son of Man be three days and three nights in the heart of the earth. The men of Nineveh will stand up at the judgment with this generation and will condemn it, because they repented at the preaching of Jonah. And now One greater than Jonah is here.

For us, then... what? When we've turned away from the Lord, and we're in "the belly of the fish" - in temptations, struggles, combats, and everything looks pretty hopeless - then if we really pray, and seek the Lord's help, he can help us.

Here's a link to an interesting (audio) sermon on this chapter, by Rev. Todd Beiswenger.

Here, too, is a link to Rev. McCurdy's study guide for the Book of Jonah, which is available for free as a .pdf, for your use.

32. Unto God and His Father, signifies by Divine truth and Divine good. This is evident from this, that "God" is the Divine truth, and "Jehovah" is the Divine good; therefore in the Word the Lord is called "God" when Divine truth is treated of, and "Jehovah" when Divine good is treated of (See Arcana Coelestia 2586, 2769, 2807, 2822, 3921, 4287, 4402, 7010, 9167); but here it is said "Father" instead of Jehovah, because the Father of the Lord was Jehovah, and by "Father" the like is meant as by "Jehovah." By both "God" and "the Father" the Lord alone is meant; for the Father was in Him as the soul is in its body (See above, n. 10, 26); since He was conceived of Jehovah, and one's soul is from him of whom He is conceived; consequently when the Lord spoke of the Father He meant His Divine in Himself. This was why He said:

That the Father is in Him and He in the Father (John 10:38; 14:10, 11).

That the Father and He are one (John 10:30).

That He is not alone, but He and the Father (John 16:32).

(That the Lord called the Divine of Jehovah, which was in Him from conception, and which was the esse of His life in His Human, "the Father," and the Divine truth which is from Divine good "the Son," see Arcana Coelestia 2803, 3704, 7499, 8328, 8897; that "the Son of man" is Divine truth, and "the Father" Divine good, see n. 1729, 1733, 2159, 2628, 2803, 2813, 3255, 3704, 7499, 8897, 9807. See also citations from Arcana Coelestia in The Doctrine of the New Jerusalem, n.304, on the unition of the Divine which is called "Jehovah," "the Father," with the Divine Human of the Lord.)