God is not just concerned about what we worship, but about HOW we worship… the end and the means. Worship a false god? Idolatry. Worship the true God in the wrong way? Idolatry.
29 “When the Lord your God cuts off before you the nations whom you go in to dispossess, and you dispossess them and dwell in their land, 30 take care that you be not ensnared to follow them, after they have been destroyed before you, and that you do not inquire about their gods, saying, ‘How did these nations serve their gods?—that I also may do the same.’ 31 You shall not worship the Lord your God in that way…
I think Jon Foreman nails this on the head in this song (adapted from Amos 5:21-23).
What should our worship look like? Again, the prophet Amos:
But let justice roll down like waters,
and righteousness like an ever-flowing stream.