In chapter 4 of the Book of Amos, verses 1-3 are talking about people who pervert the truths of the church. They will fall into falsities in outermost things.

In the Bible, fish represent "lower" things than mammals, so we can interpret the fishhooks in verse 2 as meaning being caught and held fast in natural or lower things.

Verses 4-6 are about acts of worship such as tithes and sacrifices. These look similar to genuine worship, but are only external sorts of things. We can tell because ‘teeth’ (in verse 6) represent ultimates or outermost things (see Secrets of Heaven 6380). It follows that “cleanness of teeth” would mean outermost things that look good but only imitate genuine worship. The Lord exhorts, “Yet you have not returned to me.”

Verses 7-8. Some things true will remain, when where there are too many false ideas, the truths don't get through. This can be seen where the Lord says, “I made it rain on one city; I withheld rain from another city... where it did not rain the part withered.” Again the Lord exhorts, “Yet you have not returned to me.”

Verse 9. Afterward all things of the church are falsified, shown by blight attacking the gardens, vineyards, fig tree and olive trees. The last three represent spiritual, natural and celestial things, or all the things of spiritual life. “Yet you have not returned to me,” says the Lord.

Verses 10-11. The Lord explains the devastating things he allowed to happen: plague in Egypt, death of young men by swords, stench in the camps, Sodom and Gomorrah. This is because they are profaned by sensual knowledges. Profanation means the mixing of good and evil together. (See Secrets of Heaven 1001[2]).

This extends to all things of the church, with the church being the Lord’s kingdom on earth (Secrets of Heaven 768[3]).

With profanation “as soon as any idea of what is holy arises, the idea of what is profane joins immediately to it,” (Secrets of Heaven 301).

Now there is hardly anything left. “Yet you have not returned to Me,” says the Lord again.

Verses 12-13: Because people adamantly remain in their profane ways, they are warned, “Prepare to meet your God!”. This is the God powerful and mighty, “who forms mountains, and creates the wind,” and even more close to home, “Who declares to man what his thought is.” As intimately a knowing as that is, the Lord’s love for all humanity is contained in His exhortations for them to turn themselves to Him.

See, for example, Luke 6:44-45, and True Christian Religion 373.

6380. 'And his teeth white from milk' means that the Divine Natural is nothing else than the good of truth. This is clear from the meaning of 'white' as that which is used with reference to truth, dealt with in 3301, 3993, 4007, 5319; from the meaning of 'teeth' in the genuine sense as the natural, for the hard parts of a person's body, such as his teeth, bones, and cartilages, correspond to the truths and forms of good that belong to the lowest parts of the natural; and from the meaning of 'milk' as the celestial-spiritual, or what amounts to the same, the good of truth, dealt with in 2184. The Lord's Divine Natural is said to be the good of truth when it is considered in relation to people who believe in and love the Lord; for members of the external Church are unable to go any higher in their thinking than the Lord's Divine Natural, whereas the thinking of members of the internal Church goes above the natural to the Internal. For the idea of the Lord formed by anyone who believes in Him is conditioned by how far he can rise in his thinking. Those who are aware of what the internal is can have an idea of the internal; but those who are not aware of what the internal is have an idea of the external. This is why the Lord's Divine Natural is said to be the good of truth, when in fact His entire Human is the Divine Good of Divine Love.