Note: this is a difficult passage but it seems to contrast the abominable worship in verse 17 with pure worship in verse 20. The judgements of verses 15-16 are referred to again in verse 24. The centre is the calling of all nations to Jerusalem as in Isaiah 2.
A. 15 For, behold, the LORD will come with fire, and with his chariots like a whirlwind, to render his anger with fury, and his rebuke with flames of fire. 16 For by fire and by his sword will the LORD plead with all flesh: and the slain of the LORD shall be many.
B. 17 They that sanctify themselves, and purify themselves in the gardens behind one tree in the midst, eating swine’s flesh, and the abomination, and the mouse, shall be consumed together, saith the LORD.
C. 18 For I know their works and their thoughts: it shall come, that I will gather all nations and tongues;
D. and they shall come, and see my glory.
E.19 And I will set a sign among them, and I will send those that escape of them unto the nations, to Tarshish, Pul, and Lud, that draw the bow, to Tubal, and Javan, to the isles afar off, that have not heard my fame, neither have seen my glory;
D’. and they shall declare my glory among the Gentiles.
C’.20 And they shall bring all your brethren for an offering unto the LORD out of all nations upon horses, and in chariots, and in litters, and upon mules, and upon swift beasts, to my holy mountain Jerusalem, saith the LORD,
B’. as the children of Israel bring an offering in a clean vessel into the house of the LORD. 21 And I will also take of them for priests and for Levites, saith the LORD. 22 For as the new heavens and the new earth, which I will make, shall remain before me, saith the LORD, so shall your seed and your name remain.
A’. 23 And it shall come to pass, that from one new moon to another, and from one sabbath to another, shall all flesh come to worship before me, saith the LORD. 24 And they shall go forth, and look upon the carcases of the men that have transgressed against me: for their worm shall not die, neither shall their fire be quenched; and they shall be an abhorring unto all flesh.