God possesses an absolute and intimate understanding of the nation's spiritual condition, seeing far beyond outward actions to uncover the hidden motives of the heart. Nothing is concealed from His sight, and He is fully aware of the complex dynamic between the corrupt leadership and the common people. The prophetic message is directed specifically at Ephraim, the senior and leading tribe of the Northern Kingdom. Because of its central status, which stems from the blessing Jacob gave to Joseph's sons and its strategic position on the border facing Judah in the south, the entire kingdom is frequently referred to by Ephraim's name [אבן עזרא, ביאור שטיינזלץ].
The spiritual downfall of the nation involves a clear division of responsibility between the ruling class and the masses. Ephraim represents the royal house that actively initiated the sin, while Israel represents the common people who were incited and dragged along. Through the corrupting influence of the leadership, the entire nation was led astray and became defiled with idolatry [אבן עזרא, רד״ק, מלבי״ם, ביאור שטיינזלץ]. Even though the masses were followers rather than the primary instigators, God makes it entirely clear that their actions are not hidden from Him [מלבי״ם]. Historically, this corrupt initiative began with Jeroboam son of Nebat, a king from the tribe of Ephraim. God declares His complete awareness of the secret counsels Jeroboam held with his ministers to establish the golden calves, a calculated plot designed to separate the people from serving God in the Temple [רד״ק].
While the leadership initially drove the nation into sin, a critical historical shift eventually exposed the true desires of the people [רש״י, רד״ק, מצודת דוד]. For many generations, the Israelites could excuse their idolatry and their distance from Jerusalem by claiming they were forced into it. The early kings of Israel had set up roadblocks and stationed guards to prevent anyone from making the pilgrimage. However, during the reign of King Hoshea son of Elah, those barriers were finally removed, and the road to Jerusalem was opened. Despite having the freedom to return to the Temple, the people willingly chose not to go, continuing instead in their spiritual unfaithfulness and defilement. This pivotal moment stripped away their long-held excuses, proving that their ongoing sin stemmed from their own free choice and malicious intent rather than royal coercion. With their true nature fully exposed, God knows that moral rebuke will no longer have any effect on them [מלבי״ם].