Eternal God
The first of the ten commandments that God gave to Moses and the Israelites stands out:
"You shall have no other gods before Me. You shall not make for yourself a carved image, or any likeness of anything that is in heaven above, or that is in the earth beneath, or that is in the water under the earth; you shall not bow down to them nor serve them. For I, the LORD your God, am a jealous God, visiting the iniquity of the fathers on the children to the third and fourth generations of those who hate Me, but showing mercy to thousands, to those who love Me and keep My commandments. (Exode 20:3-6, NKJV).
God told the Israelites not to have any other god but Himself and He is still the same today and forever, as John puts it: "Little children, keep yourselves from idols. Amen." (1 John 5:21, NKJV).
An idol can be a man: "because they exchanged the truth about God for a lie and worshipped and served the creature rather than the Creator, who is blessed for ever! Amen." (Romans 1:25, ESV).
Jesus said that the only true God is the Father who is worthy of all praise. When Jesus was tempted by the devil in the wilderness: "Jesus said to him: Be gone, Satan! For it is written, "You shall worship the Lord your God and him only shall you serve."" (Matthieu 4:10, ESV).