John Murray, Pictures of Christ (1961):
Secondly, pictures of Christ are in principle a violation of the second commandment. A picture of Christ, if it serves any useful purpose, must evoke some thought or feeling respecting him and, in view of what he is, this thought or feeling will be worshipful. We cannot avoid making the picture a medium of worship. But since the materials for this medium of worship are not derived from the only revelation we possess respecting Jesus, namely, Scripture, the worship is constrained by a creation of the human mind that has no revelatory warrant. This is will-worship. For the principle of the second commandment is that we are to worship God only in ways prescribed and authorized by him. It is a grievous sin to have worship constrained by a human figment, and that is what a picture of the Saviour involves.