John Calvin Commentary Deuteronomy 7:25

"The graven images of their gods shall ye burn with fire: thou shalt not covet the silver or the gold that is on them, nor take it unto thee, lest thou be snared therein; for it is an abomination to Jehovah thy God." — Deuteronomy 7:25 (ASV)

The graven images of their gods. He again impresses on them the purpose of the destruction of the nations, but he goes further than before. He had previously forbidden them to worship their gods. He now commands them to consume their graven images with fire, because the people were prone to superstition, and such snares might easily have alienated them from God’s pure worship. Nor does he command them merely to melt the gold and silver to alter its shape, but he altogether forbids its use, since it would be a contagious plague; for he shows how greatly God abominates idols, because whoever touches the materials from which they were melted would contract pollution and become accursed.

This great severity might indeed seem to condemn the metals created for human use, as if they were impure, and as if the perfection of natural things was liable to be corrupted by humanity. But in this way, idolaters would contaminate the sun and moon when falsely regarding them as objects of corrupt worship; and it must be answered that the gold and silver itself was by no means polluted by this impious abuse, but that, although free from all stain in itself, it was polluted with respect to the people. Such was the uncleanness of animals—not that they had any pollution in themselves, but because God had forbidden them to be eaten. The pollution now mentioned, therefore, arises from a similar prohibition; for otherwise, the ignorant people could not be restrained, and so God would deem abominable that which in itself was pure.

Still, this was a political precept, and only given temporarily to the ancient people; yet we gather from it how detestable idolatry is, which even infects the works of God themselves with its own filthiness.