'Unclean' in the Bible

Then Haggai said, “If one who is [ceremonially] unclean because of [contact with] a corpse touches any of these [articles of food], will it be unclean?” And the priests answered, “It will be unclean.” [Ceremonial uncleanness, like sin, is infectious.]

Then Haggai answered, “‘So is this people. And so is this nation before Me,’ declares the Lord, ‘and so is every work of their hands; and what they offer there [on the altar] is unclean [because they who offer it are unclean].