Icons: Objects for Veneration or Mere Decoration?

Recently I have come across an anti-Orthodox polemic which rejects our veneration of icons on the grounds that venerating an image painted on a board of Christ, His Mother, or His saints is contrary to the practice of the apostles and of the earliest Church. The objection is stated with some sophistication, and is not the usual fundamentalist reference to the Mosaic Law’s proscription of carved statues used in worship (e.g. Exodus 20:4f). This more sophisticated objection acknowledges that there were indeed images of Christ, His Mother, and His saints used in the early Church such as can be found in the funerary art of the catacombs and on the walls of churches (such as that of Dura Europos). But, it points out, there is no evidence that these images functioned as anything more than mere decoration. That is, the people did not come up to the wall to kiss the wall art or venerate the images.