It is easy to be an idolator. All one has to do is serve the image of God instead of God himself. This is not very hard to do since we humans have a propensity and an inherent knack for creating idols. God is an eternal, ineffable, infinite, undefinable entity. This is just another way of saying "we really cannot define what God is." All we can really say about God is that God is. To say anything more is to define God which of course is quite impossible. We might say things like "God is love" but when we say such things we do not intend to define God as love but to indicate something about who he is. To define God is idolatry because defining something is giving something a definition of limited bounds and of course God is boundless and cannot be bound. To define God is an attempt to put God in a box and make for one's self an image of God to serve because we cannot comprehend the reality of God and so we try to find another way which suits our fancies of God.
We tend to do this of course because we think we must "believe" and believing requires knowledge, hopefully true knowledge, which we humans call "truth" and believing is the act of uniting with truth. Faith is union with knowledge and true faith union with true knowledge, that is, truth. So when we believe things about God we are believing things about our perceived image of God that we have in our minds. Believing things about God is not what the early Christians meant when they used the phrase "believe in God." And so we commit idolatry if this is the reality of our faith. Ideas about God are but his mirror reflection, his image, and not his reality. To unite to conceptual truths about God as the means of faith is to unite to the image of God. To unite to God is to unite to the reality of truth, God himself, not the image of our concepts about him, but God himself. Thus true faith is union with God, not simply union with things about the person and reality of God. Our concepts about God are images of God and if these images become what we think God is, we are idolators, especially if God becomes our perception of him, an image of him we have created for ourselves.
Many "Christians" today are idolators. It is easy to spot them, and as is the case with all idolators, they don't know any better. They will jump up and down madly if someone comes along with a different conceptual image of God than they have and insist a different God is being worshiped and hence their idolatry is instantly exposed. If their conceptual image of God is a Trinity of Father, Son and Holy Ghost and yours is not, then they will insist you worship a different God. Now think about this carefully. They are demanding that their image of God is the true God. They are further insisting that their definition of God is the right definition. In other words, they have defined God for themselves. But God is undefinable and therefore they worship an image instead of the Creator and they are deceived into worshiping an idol. And as such they demand that one worship their idol instead of another idol of God. They demand their image be served and not another. And images of God served is idolatry.
God is not an image in our mind but a reality that is something other than the image in our mind. To suppose that God is only worshiped by someone if their image of God conforms to the image in our own mind is to confess our own idolatry because we infer God is a truthful conceptual image of God. We follow instead our own creation, instead of the Creator.