This was the problem that the prophet Malachi, in the last of the minor prophets (as well as the final book of the Old Testament), deals with. Sin had hardened the hearts of God's people, and the priests that served in His temple. The sacrifices made were substandard. The tears shed on the altar were fake. Even their personal lives showed a lack of understanding God and His ways. All this adds up to robbing our God of what's due Him.
To fail to see that God is holy, and righteous, and that He calls His people to reflect His character, means that we make a mockery of our Lord. God created us to be a reflection of Himself. But sin tarnishes that image.
Only those who repent of sin and give God what is due Him will be spared. For His messenger is coming, proclaiming the One who will bring about righteousness and holiness.