Paul urges us to put earthly desires to death, giving a list of sins. That list concludes by saying to put aside covetousness which is idolatry. Covetousness began in the Garden when the woman desired to be like God, knowing good from evil. Today, in order to justify our desires either for things that God has forbidden or for things belonging to another, we turn to other 'gods' for justification. Hence covetousness becomes the impulse for idol worship.