What does Malachi 2:12 mean?
Malachi's message is being delivered to a spiritually dead nation. The priests are apathetic and knowingly offer impure sacrifices (Malachi 1:7–8). The people are unfaithful to God (Malachi 2:11), and to each other (Malachi 1:10). One of the most serious sins being committed is marrying pagans (Malachi 2:11). This is a heinous crime in the eyes of God, because marriage is meant, in part, to symbolize the relationship between man and God. God's holiness and love can't mean much to a person willing to join with a person who rejects the truth in favor of idols.This is a serious offense, and verse 12 invokes a curse on those who commit it. To be "cut off" was a metaphor for death, either spiritual or physical. This might be a separation from the nation of Israel, or an end to that man's family line. Either way, the consequences of pagan intermarriage were severe.
Note, also, that this verse includes a jeer at the attitude of Israel. Pagan intermarriage is a clear-cut sin, and a violation of the Law. And yet, men who commit this crime have the nerve to bring offerings to God, seeking His favor. This is a sign of Israel's spiritual decay.
Malachi 2:10–16 is perhaps the Bible's strongest indicator of God's views on divorce. This passage begins the second of Malachi's three prophetic lessons, ending in Malachi 3:6. The people of Israel are rebuilding Jerusalem and the temple, but under the control of a foreign nation. Rather than honoring God, and their own wives, it seems the men of Israel were divorcing Jewish women in order to marry pagans (Ezra 9:1–2; Nehemiah 13:23–27). This is described in this passage as an act of violence against the women. In no uncertain terms, Malachi expresses God's hatred for divorce.
God will humiliate the priests who are insulting Him with improper sacrifices. While the priests are being unfaithful to God, the people of Israel are also being unfaithful to each other. In particular, they are marrying pagans, and committing divorce, which God absolutely despises. God's covenant with Israel included both blessings for obedience, and consequences for disobedience. And yet, as Israel disobeys, they blame God for their hardships. God's people are defying Him, then blaming Him for the end results!