Albert Barnes 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)

Ask now the priests concerning the law - The priests answer rightly, that by the law, insulated unholiness spread further than insulated holiness. The flesh of the sacrifice hallowed whatever it should touch, but not further; but the human being, who was defiled by touching a dead body, defiled all he might touch (Numbers 19:22).

Haggai does not apply the first part; namely, that the worship on the altar which they reared, while they neglected the building of the temple, did not hallow. The possession of a truly holy thing does not counterbalance disobedience. On the contrary, one defilement defiled the whole man and all which he touched, according to that (James 2:10), “whosoever shall keep the whole law and yet offend in one point, he is guilty of all.”

In the application, the two melt into one, for the holy thing, namely, the altar which they raised out of fear on their return, so far from hallowing the land or people by the sacrifices offered on it, was itself defiled. “This people” and “this nation” (not “My people”) since they by their actions disowned Him. “Whatever they offer there,” that is, on that altar, instead of the temple which God commanded, is unclean, offending Him who gave all.