God is concerned not only with heart motive—although that is certainly central—nor is he simply concerned that people worship him alone—although that is, of course, true. He is also concerned that his people worship him in the right way, which includes not worshiping in ways that he has forbidden or inventing new ways to worship that he has not commanded.
In the Old Testament Law, God gave his people very specific instructions about how they were to relate to the people around them, including in their culture and worship practices.
Deuteronomy 12:2–8 reveals important principles in this regard. God commanded that the people destroy the places where pagans worshiped, including their altars, their pillars, their images, and even the names of the places. This is clearly more than simply insisting that they worship Yahweh rather than false gods; this is stark evidence that God rejects worship that imitates pagan worship in any way. Everything in pagan culture embodies religious commitments, and those elements that are imbibed with pagan religious meaning must be rejected for use in worship. One might ask why they had to destroy, for example, the altars and pillars; wouldn’t these be useful even for the worship of the true God? Yet God commanded that they be destroyed. He summarized his desires with the words, “You shall not worship the LORD your God in that way.” Instead, they were to listen to his instructions and find a place of his choosing for their worship.
Yet the people disobeyed these principles even as they waited at the foot of the mountain for Moses to return from receiving the law tablets. The golden calf incident is a terrible failure for this newly formed worship community, but unfortunately one that foreshadows many other failures in the days and years ahead. Fearing that Moses would never come back, the people demanded a physical representation of deity, just like the pagan nations had. Aaron complied, forming a golden calf, similar to the practice of both Egypt and Canaan, and the people celebrated with an orgiastic festival so noisy that it sounded to Joshua’s ears from a distance like “a noise of war in the camp.”