A delegation of Israelite leaders confronts the two and a half tribes with a severe accusation, viewing the construction of a new altar as a deep spiritual and national crisis. The leaders demand to understand the motive behind this act, which they see as a direct threat to the unity of the nation and its loyalty to God. The heavy suspicion stems primarily from the silence of the builders. Because they built the structure together without revealing their good intentions in advance, they left room for the rest of the nation to suspect them of deep betrayal [חומת אנך].
The confrontation is framed in harsh terms of sin, crime, and turning away, with the very act of building the altar viewed as a direct rebellion against God [מצודת ציון, ביאור שטיינזלץ, מצודת דוד]. The leaders speak at length because they do not know the true purpose of the altar, forcing them to address two different possibilities [מלבי״ם, אלשיך, אברבנאל].
The first possibility is that the altar was built for idol worship. If true, this represents a double sin: the passive abandonment of God combined with an active rebellion through the worship of other gods [אברבנאל]. The leaders are shocked by the boldness of such a rebellion happening right at that moment, while the fresh miracles God performed for them are still right in front of their eyes [מלבי״ם]. This concern carries a broader warning that simply pulling back and becoming lazy in the service of God will inevitably lead, step by step, to open and active rebellion [אלשיך].
The second possibility is that the altar was not meant for idols, but rather to offer sacrifices to God. Yet, even in this scenario, building an altar outside the Tabernacle is considered an act of rebellion. By doing so, the two and a half tribes are creating an independent center of worship. This action rejects the shared spiritual center of the entire nation and creates a dangerous divide between them and the rest of the Israelite tribes [ביאור שטיינזלץ, אלשיך].