“And if the prophet is deceived and speaks a word, I Yahweh have deceived that prophet, and I will stretch out my hand on him, and will destroy him from among my people Israel. And they will bear their iniquity. The iniquity of the prophet will be on the same level as the iniquity of the one who seeks to him.”
For those who persisted in idolatry God would even provide false prophets, prophets who were deceived. In a sense people receive the teachers that they deserve. If they do not want God's pure word, then God will allow them teachers who go astray from the word. And both the teachers and they will be destroyed together. Judgment will come on them and they will be rooted out from among God's people. And from it God's people will learn their lesson.
‘I Yahweh have deceived that prophet.' This could be said because God was seen as the ‘first cause' of everything. We would say ‘He allowed it'. The prophet would be deceived because his mind was closed to God and he was a man-pleaser not a God-pleaser (Isaiah 8:20). That was not God's doing. The people would have false prophets because they did not want to listen to true prophets. They would choose them for themselves. But God would allow it because they had first chosen their own way and closed their minds to the truth. If they hardened their hearts, God would allow more things that would further harden their hearts. The judgment of God on those who pursued idolatry would be in allowing them to continue in it until it destroyed them (compare Leviticus 20:3-6; Deuteronomy 28:36; Hosea 4:17; and see Paul's vivid description of the process for all nations in Romans 1:18-32). Thus in the end what happened was in the permissive will of God (compare Isaiah 45:7; Amos 3:6).