Question: "Why was the altar in Joshua 22:10–34 such a big deal?"
Answer: When God revealed the Law of Moses, He prohibited the building of altars other than those He had commanded (Deuteronomy 12:1–14). Yet in Joshua 22 the tribes on the east side of the Jordan River constructed an altar. As a result, the western tribes felt the Law had been violated and intended to go to war against their own people.
Why would these western tribes consider such a strong response? The answer is found in Deuteronomy 13:12–16 that commands, “If you hear it said about one of the towns the Lord your God is giving you to live in that troublemakers have arisen among you and have led the people of their town astray, saying, ‘Let us go and worship other gods’ (gods you have not known), then you must inquire, probe and investigate it thoroughly. And if it is true and it has been proved that this detestable thing has been done among you, you must certainly put to the sword all who live in that town. You must destroy it completely, both its people and its livestock. You are to gather all the plunder of the town into the middle of the public square and completely burn the town and all its plunder as a whole burnt offering to the Lord your God. That town is to remain a ruin forever, never to be rebuilt.”
The western tribal leaders followed this law exactly. They heard of an altar they thought was an attempt at idol worship. They investigated the allegation to discover the truth of the situation. Then they found out the altar was a memorial to the Lord God. The eastern tribes had built the altar to show their connection to the rest of the Israelites who lived in the Promised Land.
When the matter was concluded, we read that the high priest, Phinehas, replied, “Today we know that the LORD is with us, because you have not been unfaithful to the LORD in this matter. Now you have rescued the Israelites from the LORD’s hand” (Joshua 22:31). Phinehas cleared these tribes of all charges. The chapter summarizes, “They were glad to hear the report and praised God. And they talked no more about going to war against them to devastate the country where the Reubenites and the Gadites lived” (Joshua 22:33).
This interesting example stands in contrast with the later actions of the Israelites. The following book, the Book of Judges, reveals that idol worship soon became common among the Israelites, leading to God’s judgment upon them. Yet, in this early stage of Israel’s possession of the Promised Land, they quickly sought to obey God’s laws. While today’s Christians do not live under the Mosaic Law, the principle of obedience to God remains. We are called to study the Scriptures and live out its principles.