William Ames writing in his Marrow of Theology discusses image worship:
Prayer is opposed by the use of representative images at or before which God is worshiped, even though the worship is referred not to the images themselves – subjectively, as some say – but objectively to God alone.
Superstition of this type is called idolatry, Exod. 32:5; Ps. 106:20; Acts 7:41.
If idols are themselves worshiped instead of God, this is the idolatry which violates the first commandment. If the true God is worshiped at an image or in an image, this is the idolatry which violates the second commandment.
Although such a worshiper does not in intention offend against the primary or highest object in worship, yet from the nature of the thing itself he always offends against the formal worship of God. In his mind a new God, who is delighted with such worship, is imagined as the object of his adoration; religious worship is also given to the image itself. This occurs even when the worship is not considered to be ultimately bound up with the image but is directed to God himself.