Isaiah 66:17 - Matthew Poole's English Annotations on the Holy Bible

That the Jews might not think that the judgments threatened concerned only the heathen, he tells them they concerned them, the idol worshippers amongst them; and not idolaters only, but such as broke his laws about meats, which he had prohibited them to eat. Those that sanctified and purified themselves in gardens, gardens in which they worshipped idols, Isaiah 1:29, Isaiah 65:3,4 1 Kings 14:23, 1 Kings 15:13: the word translated gardens signifieth such as were thick planted with trees, and had groves in them, where they set their idols, 1 Kings 15:13; hence the idol is called the grove, 2 Kings 23:6; they had also in these gardens pools, where they washed themselves in a way of preparation for their idol worship, as the priest by God's ordinance was to bathe himself, Numbers 19:7. Behind one tree in the midst; behind one of the trees, or one by one behind the trees. Some think that Achar is here a proper name of an idol, behind which or behind whose temple these idolaters were wont to purify themselves. These gardens were places too as well for brutish lusts as idol worship, as may be learned from 1 Kings 14:24 2 Kings 23:7, and they by these washings thought to make themselves clean. Eating swine's flesh, forbidden Leviticus 11:7 Deuteronomy 14:8. And the abomination; either any abominable things, or all those beasts forbidden the Jews for meat, Leviticus 11:9,10, &c. Some think a particular abominable thing is here meant, and think it is the weasel, which, Leviticus 11:29, is joined with the mouse, which is here next mentioned. The word which we translate mouse being no where found but there, and here, and 1 Samuel 6:4,5,11,18, some think it is not that creature we call a mouse, (because a mouse is properly no creeping thing; but the word, Leviticus 11:29, signifieth a creeping thing,) they therefore think it rather signifieth some serpent. It is a matter of no great consequence. The sense is, that God would not only destroy the open and gross idolaters and superstitious persons, but all those also who had made no conscience of yielding obedience to the law of God in such things as seemed to them of a minute nature, and such as they easily might have yielded obedience to; he saith that they shall all perish together. In the day of judgment, the idolatrous pagan and papist, and the lewd anti disobedient protestant, shall fare alike. It will be a hard thing for a thinking soul to see how baptism, and a membership in the Christian church, should save men from God's wrath, without holiness, more than circumcision and membership in the Jewish church.