The tribes accused of building a rival altar answer with horror at the thought. A community that keeps two altars serves two masters, and a divided center cannot hold a people together. One place of sacrifice means one order of value, one shared account of what stands highest. Worship cannot be split.
The men here defend that single center as if their lives depended on it, because they do. Split the highest good into competing versions and every lesser quarrel becomes a war with no referee. The wish to worship alongside the sacred altar hides a slow drift away from it. Loyalty to what is highest has to be undivided, or it stops being loyalty at all.