What is the definition of idolatry?

TL;DR:

Idolatry is giving worship, devotion, or priority to anything other than God. Whether physical idols or pursuits like money, pride, or success, anything we elevate above Him becomes a false god in our hearts.

what does the bible say?

Idolatry is the worship of anything other than God, whether physical idols or misplaced priorities. God forbade idolatry in the Mosaic Law as part of the Ten Commandments (Exodus 20:3-5). In the Old Testament, God commanded Israel to destroy altars and high places of false gods to protect their purity (Deuteronomy 12:2–3; Exodus 34:13), but the people often fell into idol worship themselves (Exodus 32:1-6; 1 Kings 12:28-30). The New Testament shows that idolatry includes covetousness and anything we value more than God (Colossians 3:5). While idols of stone and wood are powerless, the danger lies in our hearts when we give created things the devotion and priority that belongs to God. Idolatry can take the form of money, pride, success, or even good things elevated above God, reminding us that only He is sufficient to satisfy.

from the old testament

God instructed His people, "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 or serve them, for I the LORD your God am a jealous God" (Exodus 20:3-5a). Many of the Old Testament commands against idolatry refer specifically to physical idols, such as those that would have been present in the pagan nations surrounding the Israelites.
Because idol worship was such a threat to the Israelites' purity, God even instructed His people to destroy the pagan nations they conquered and to refrain from intermarrying (Deuteronomy 7:1-5).
The Israelites were commanded to destroy the places of idol worship, tearing down altars and high places built for false gods (Deuteronomy 12:2–3; Exodus 34:13).
Unfortunately, the Israelites did not always follow God's commands, and fell into the trap of worshipping physical idols, even creating one of their own (Exodus 32). The Old Testament is, in some ways, a chronicle of the Israelites' moves away from and back to God.

from the new testament

Idolatry wasn’t just a temptation for the Old Testament Israelites. Paul warns the Corinthians to “flee from idolatry” (1 Corinthians 10:14).
After asserting that “him who is true” is Christ, John warns believers against idolatry (1 John 5:21).
Colossians 3:5 links idolatry with covetousness; when we want something so much that we covet it, that thing has become an idol. We seek it rather than God.

implications for today

Even if we are not bowing down to physical images of false gods, idolatry is still an issue today. MacArthur defines idolatry, in part, as anything which causes us to think less of God (paraphrased). Idolatry is anything we prioritize above God. Today, some of our idols are pride, money, popularity, body image, hobbies, and the like. Many of these, in themselves, may not be bad. We need money in order to live (Matthew 6:31-33); caring for our bodies is appropriate (1 Corinthians 6:19-20); God is a giver of good gifts, and we can take delight in the hobbies He has given us (James 1:17; Psalm 37:4). However, when we begin to value something above God, when we give it prominence and priority in our lives, when we expect that thing to provide us with ultimate satisfaction (even if that expectation is not voiced), we have begun making it into an idol. God alone is sufficient for all our needs. The other things are gifts, not gods.

understand

Idolatry is worshiping or prioritizing anything other than God.
The Bible condemns idolatry because it leads us away from God.
Only God is worthy of worship, and only God can truly satisfy.

reflect

What are some things in your life that may be competing with God for your devotion and priority?
How do you respond when you realize that you have placed greater value on something created rather than on God?
How can you refocus your worship and satisfaction on God alone this week?

engage

How does God’s commands to destroy physical idols help us understand God’s seriousness about idolatry?
How does the New Testament expand the meaning of idolatry beyond physical images?
How can we discern the difference between enjoying God’s good gifts and turning them into idols?