'Unclean' in the Bible

Then Haggai asked, "If a person who is ritually unclean because of touching a dead body comes in contact with one of these items, will it become unclean?" The priests answered, "It will be unclean."

Then Haggai responded, "'The people of this nation are unclean in my sight,' says the Lord. 'And so is all their effort; everything they offer is also unclean.