“they have set their abominations.” This is restated in Jeremiah 32:34.
“the house that is called by my name.” That is, the Temple.
“to defile it.” This is the reading of the Hebrew text of Jeremiah 7:30, and it cannot be ignored. While some modern versions change to the wording to “and defiled it” (cp. HCSB), and that certainly was a result of the abominations set up in the Temple, we cannot set aside the meaning of the Hebrew text that there were certainly at least some of the ungodly priests, prophets, and leaders that were in league with the Devil and put abominations in Yahweh’s Temple with the evil intent of defiling it.
The world is in a war between Good and Evil, and while many people who do evil things do them in ignorance of the spiritual realities, there are many evil people who know full well the evil that they do and do them intentionally to defy God, and to hurt God’s people. For example, the Jewish leaders at the time of Christ knew they were setting aside the commandments of God to keep their traditions (Mark 7:9).