Summary: Malachi points out how the people were mistreated each other because they were not right with God.
In the Great Commandment, Jesus says that commitment to our love relationship with God positively impacts our relationship with others.
“Jesus replied, ‘You must love the LORD your God with all your heart, all your soul, and all your mind.’ This is the first and greatest commandment. A second is equally important: ‘Love your neighbor as yourself.’” - Matthew 22:37-39 (NIV)
But the opposite is also true - a negative relationship with God will negatively impact my relationship with others. Note verse 10.
“Have we not all one Father? Has not one God created us? Why then do we deal faithlessly and treacherously each against his brother, profaning the covenant of [God with] our fathers?”
- Malachi 2:10 (Amplified)
If we are not right with God, it will be reflected in the choices we make in our relationship with others. Malachi cites three such choices being made by the people of his day.
1. They were choosing compromise over conviction - vs. 11-12
Malachi says they had desecrated the Lord’s sanctuary by their practice of idolatry. In accepting other gods as being equal to Yahweh, they were saying, in effect, that He was not holy or separate or superior to the false gods of their pagan neighbors.
I think it is important to note that the problem here was not interracial marriage. A mixed multitude went out of Egypt with the Israelites (Exodus 12:38), but they committed themselves to Jehovah (Exodus 12:48; Numbers 9:14). Boaz married Ruth the Moabitess, but she had forsaken the false gods of her people for Israel’s God (Ruth 1:16).
But, these Israelites were marrying women who remain devoted to their false gods. The problem wasn’t interracial marriage, but interfaith marriage. Malachi says that the Lord would “cut off from the tents of Jacob” whoever it was who “marry the daughter of a foreign god.”
This judgment of God on those who married unbelievers is really one where He allows them to experience the consequences of their choice. The fact was, you see, that no matter who they were in the nation of Israel, they would find themselves cut off simply by virtue of the fact that the compromise they had made in choosing the unbeliever over the Lord would be a choice fraught with problems.
There was a reason God forbade intermarriage with unbelievers then and a reason God forbids it now. Paul makes clear what that reason is:
“Don’t team up with those who are unbelievers. How can righteousness be a partner with wickedness? How can light live with darkness? What harmony can there be between Christ and the devil? How can a believer be a partner with an unbeliever?” - 2 Corinthians 6:14-15 (NLT)
The judgment upon those who marry unbelievers is this: it is difficult to walk with God when your spouse is pulling you in the opposite direction. Which is why God says they would find that they had, by virtue of this choice, made it difficult to walk with God and His people, “even though he brings offerings to the Lord Almighty.”