“Then Haggai responded, ‘The people of this nation are unclean in my sight,’ decrees the Lord. ‘And so is all their effort; everything they offer is also unclean.'”
An unclean people cannot offer to God sacrifices or offerings that are acceptable. Everything becomes contaminated. Man’s opinion does not matter. It is what God sees that counts.
Sinners cannot dig themselves out of their sin. We all sin, Rm 3.23. Our every effort is therefore repulsive to God. We have no merit; we need saving grace.