I have noticed that the vast majority of Christians I encounter are engaged in idolatry, and don't know it. True story follows.
During this past Easter season, a piece of artwork depicting Jesus praying in the garden of Gethsemane disappeared from its usual location. One particular person was highly disturbed. This person ranted and raved, waving their arms about claiming that someone had taken down the picture of Jesus. "Who could it have been!?", they cried. "Who could it have been!?" This person questioned everyone around them. No one knew the answer. This person returned everyday for 7 days, questioning everyone available as to the whereabouts of the picture of Jesus. No one had an answer, the picture was just simply gone. This person then concluded it had to have been someone from the outside. Someone from outside had come in and stolen the picture of Jesus. After about 3 weeks on the subject, the person finally lost some steam concerning the picture. Eventually another picture of Jesus, just like the one that had disappeared was found. It was hung in the same location as the previous picture. When the person entered the room and saw the new picture in the same location, they clapped their hands together, and hurried over to it. They then reached out, touched the picture, and closed their eyes and prayed, saying it was a miracle that the picture had returned.
This person was convinced the picture of Jesus was an actual depiction of what Jesus looked like. This became the image that they worshiped. This is idolatry.