John Calvin Commentary Joshua 22:16

"Thus saith the whole congregation of Jehovah, What trespass is this that ye have committed against the God of Israel, to turn away this day from following Jehovah, in that ye have builded you an altar, to rebel this day against Jehovah?" — Joshua 22:16 (ASV)

Thus says the whole congregation, etc. Just as if it had been known that this second altar was opposed to the one and only altar of God, they begin by reproaching them, and that in a very harsh and severe manner. They therefore assume it was an admitted fact that the two tribes had built the altar with the intention of offering sacrifices on it.

In this they are mistaken, as it was destined for a different use and purpose. Moreover, if the idea they had conceived had been correct, all the remonstrance they employ would have been just; for it was a clear case of criminal revolt to make any change in the Law of God, who values obedience more than all sacrifices (1 Samuel 15:22), and there would have been perfect grounds for condemning them as apostates for withdrawing from the one and only altar.