Charles Spurgeon Commentary Haggai 2:11-14

"Thus saith Jehovah of hosts: Ask now the priests concerning the law, saying, If one bear holy flesh in the skirt of his garment, and with his skirt do touch bread, or pottage, or wine, or oil, or any food, shall it become holy? And the priests answered and said, No. Then said Haggai, If one that is unclean by reason of a dead body touch any of these, shall it be unclean? And the priests answered and said, It shall be unclean. Then answered Haggai and said, So is this people, and so is this nation before me, saith Jehovah; and so is every work of their hands; and that which they offer there is unclean." — Haggai 2:11-14 (ASV)

That which is ceremonially holy cannot communicate its holiness to that which is unclean; but that which is unclean, in the eyes of the law, can communicate its uncleanness to anything that touches it. These people, being themselves defiled with sin, could not bring to God either acceptable service or acceptable offerings.