By cleansing Israel, God would remove their past habit of idol worship, giving them a new heart to worship only God (Jeremiah 31:33; 32:38–40; Ezekiel 36:25–28).
In biblical times, a person's name represented their existence. When people forget the names of idols, the idols no longer exist.
False prophets misrepresented God by creating fake divine messages or speaking in the name of other gods (Deuteronomy 13:5–11; 18:17–22). They led Israel away from God by promoting idol worship (Jeremiah 23:13, 25) and would continue to do so (see Nehemiah 6:12–14; Mark 13:22; 2 Peter 2:1; 1 John 4:1–3) until the day of the Lord.