Commentators unanimously point out that the Israelites were not trying to worship a new god, but were attempting to worship Jehovah through the golden calf. Aaron's declaration of 'a feast to Jehovah' makes this clear. Their sin was syncretism—mixing true worship with pagan forms—which is a direct violation of the second commandment's prohibition against graven images. This shows that idolatry isn't just abandoning God, but also corrupting how He is to be worshipped.