Isa 66:17 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.
One might wonder where today we might find these Christians purifying themselves in the gardens and eating mice?
They that sanctify themselves - That is, who attempt to purify themselves by idolatrous rites, by ablutions, and lustrations. The design here is, to describe those who will be exposed to the wrath of God when he shall come to execute vengeance. Barnes
Eating swine’s flesh (comp. Isa_65:4). And the abomination. The word is used generically of all the "abominable things" forbidden to be eaten in Le Isa_11:4 -30, as the camel, the coney, the hare, the eagle, the vulture, the ferret, the chameleon, the lizard, etc. Pulpit Commentary
Isa 65:3 A people that provoketh me to anger continually to my face; that sacrificeth in gardens, and burneth incense upon altars of brick;
Isa 65:4 Which remain among the graves, and lodge in the monuments, which eat swine's flesh, and broth of abominable things is in their vessels;
Obviously speaking of the Jews under the Mosaic Law....