John Calvin on Why God Forbids Images of Him

"When once men imagined that they beheld God in images, they also worshiped him as being there.  At length their eyes and minds becoming wholly engrossed by them, they began to grow more and more brutish, gazing and wondering as if some divinity were actually before them.  It hence appears that men do not fall away to the worship of images until they have [swallowed] some idea of a grosser description: not that they actually believe them to be gods, but the the power of divinity somehow or other resides in them.  Therefore, whether it be God or a creature that is imaged, the moment you fall prostrate before it in veneration, you are so far fascinated by superstition.  For this reason, the Lord not only forbade the erection of statues to himself, but also the consecration of titles and stones which might be set up for adoration.  For as soon as a visible form is given to God, his power also is supposed to be annexed to it.  So stupid are men, that wherever they figure God, there they fix him, and by necessary consequence proceed to adore him.  It makes no difference whether they worship the idol simply, or God in the idol; it is always idolatry when divine honors are paid to an idol, be the color what it may.  And because God wills not to be worshiped superstitiously, whatever is bestowed upon idols is so much robbed from him" (Institutes of the Christian Religion, John Calvin).

John Calvin on Three Main Attributes of God

"God, the Creator of heaven and earth, governs the world which was made by him.  In every part of Scripture we meet with descriptions of his paternal kindness and readiness to do good, and we also meet with examples of severity which show that he is the just punisher of the wicked, especially when they continue obstinate notwithstanding all his forbearance.

"Assuredly, the attributes [of God] which it is most necessary for us to know are these three: loving-kindness, on which alone our entire safety depends; judgment, which is daily exercised on the wicked, and awaits them in a severer form, even for eternal destruction; righteousness, by which the faithful are preserved, and most benignly cherished.  The prophet declares, that when you understand these, you are amply furnished with the means of glorying in God.  Nor is there here any omission of his truth, or power, or holiness, or goodness.  For how could this knowledge of his loving-kindness, judgment, and righteousness exist, if it were not founded on his [incorruptable] truth?" (Institutes of the Christian Religion, John Calvin).