More specifically and destructively, it is polytheism against God:
Exodus 20:3 "Hear O Israel, the Lord, Our God is One." Deuteronomy 6:4
Isaiah 45:5 "I alone am the Lord, beside me, there is no other god!"
Hosea 13:4 Isaiah 43: 11 "I am the Lord, there is no other Savior. You shall know of...