There are those who would argue that the systematic theology of the Reformed is simply scripture. Not quite true. Calvin is a good example, for he stuck close to the Bible, but in the consideration of systematic theology you have to demonstrate why one would worship God, and why his word is authoritative -- which too a very long chapter (chapter eight) that I split in three.
The question is why we should chase God. The simple reason is that he alone is worthy of our love and trust. We will never be perfect. But we all should God seek.
When the mind becomes attached to a thing with intense love and desire, the result is that it sets aside other things. So, from the fact that man’s mind is fervently inclined by love and desire to divine matters, in which it is obvious that perfection is located, it follows that he casts aside everything that might hold him back from this inclination to God: not only concern for things, for wife, and the love of offspring, but even for himself. And the words of Scripture suggest this, for it is said in the Canticle of Canticles (8:7): “if a man should give all the substance of his house for love, he will account it as nothing”; and in Matthew (13:45): “the kingdom of heaven is like to a merchant seeking good pearls, who, when he found one pearl of great price, went his way and sold all that he had and bought it”; and also in Philippians (3:7-8): “the things that were gain to me… I counted as dung, that I might gain Christ.”
Thomas Aquinas, at Brigg's place
Our God is glorious and worthy of worship, and him alone. So let's look at our French Hugenot, sitting in Geneva.
1. WE formerly observed that the knowledge of God, which, in other respects, is not obscurely exhibited in the frame of the world, and in all the creatures, is more clearly and familiarly explained by the word. It may now be proper to show, that in Scripture the Lord represents himself in the same character in which we have already seen that he is delineated in his works. A full discussion of this subject would occupy a large space. But it will here be sufficient to furnish a kind of index, by attending to which the pious reader may be enabled to understand what knowledge of God he ought chiefly to search for in Scripture, and be directed as to the mode of conducting the search. I am not now adverting to the peculiar covenant by which God distinguished the race of Abraham from the rest of the nations. For when by gratuitous adoption he admitted those who were enemies to the rank of sons, he even then acted in the character of a Redeemer. At present, however, we are employed in considering that knowledge which stops short at the creation of the world, without ascending to Christ the Mediator. But though it will soon be necessary to quote certain passages from the New Testament (proofs being there given both of the power of God the Creator, and of his providence in the preservation of what he originally created), I wish the reader to remember what my present purpose is, that he may not wander from the proper subject. Briefly, then, it will be sufficient for him at present to understand how 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 of all his forbearance.
2. There are certain passages which contain more vivid descriptions of the divine character, setting it before us as if his genuine countenance were visibly portrayed. Moses, indeed, seems to have intended briefly to comprehend whatever may be known of God by man, when he said, "The Lord, The Lord God, merciful and gracious, long-suffering, and abundant in goodness and truth, keeping mercy for thousands, forgiving iniquity and transgression and sin, and that will by no means clear the guilty; visiting the iniquity of the fathers upon the children, and upon the children's children, unto the third and to the fourth generation," (Ex. 34:6, 7). Here we may observe, first, that his eternity and selfexistence are declared by his magnificent name twice repeated; and, secondly, that in the enumeration of his perfections, he is described not as he is in himself, but in relation to us, in order that our acknowledgement of him may be more a vivid actual impression than empty visionary speculation. Moreover, the perfections thus enumerated are just those which we saw shining in the heavens, and on the earth--compassion, goodness, mercy, justice, Judgment, and truth. For power and energy are comprehended under the name Jehovah. Similar epithets are employed by the prophets when they would fully declare his sacred name. Not to collect a great number of passages, it may suffice at present to refer to one Psalm (145) in which a summary of the divine perfections is so carefully given that not one seems to have been omitted. Still, however, every perfection there set down may be contemplated in creation; and, hence, such as we feel him to be when experience is our guide, such he declares himself to be by his word. In Jeremiah, where God proclaims the character in which he would have us to acknowledge him, though the description is not so full, it is substantially the same. "Let him that glorieth," says he, "glory in this, that he understandeth and knoweth me, that I am the Lord which exercise loving-kindness, Judgment, and righteousness, in the earth," (Jer. 9:24). Assuredly, the attributes 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 inviolable truth? How, again, could it be believed that he governs the earth with Judgment and righteousness, without presupposing his mighty power? Whence, too, his loving-kindness, but from his goodness? In fine, if all his ways are loving-kindness, Judgment, and righteousness, his holiness also is thereby conspicuous. Moreover, the knowledge of God, which is set before us in the Scriptures, is designed for the same purpose as that which shines in creation--viz. that we may thereby learn to worship him with perfect integrity of heart and unfeigned obedience, and also to depend entirely on his goodness.
3. Here it may be proper to give a summary of the general doctrine. First, then, let the reader observe that the Scripture, in order to direct us to the true God, distinctly excludes and rejects all the gods of the heathen, because religion was universally adulterated in almost every age. It is true, indeed, that the name of one God was everywhere known and celebrated. For those who worshipped a multitude of gods, whenever they spoke the genuine language of nature, simply used the name god, as if they had thought one god sufficient. And this is shrewdly noticed by Justin Martyr, who, to the same effect, wrote a treatise, entitled, On the Monarchy of God, in which he shows, by a great variety of evidence, that the unity of God is engraven on the hearts of all. Tertullian also proves the same thing from the common forms of speech. But as all, without exception, have in the vanity of their minds rushed or been dragged into lying fictions, these impressions, as to the unity of God, whatever they may have naturally been, have had no further effect than to render men inexcusable. The wisest plainly discover the vague wanderings of their minds when they express a wish for any kind of Deity, and thus offer up their prayers to unknown gods. And then, in imagining a manifold nature in God, though their ideas concerning Jupiter, Mercury, Venus, Minerva, and others, were not so absurd as those of the rude vulgar, they were by no means free from the delusions of the devil. We have elsewhere observed, that however subtle the evasions devised by philosophers, they cannot do away with the charge of rebellion, in that all of them have corrupted the truth of God. For this reason, Habakkuk (2:20), after condemning all idols, orders men to seek God in his temple, that the faithful may acknowledge none but Him, who has manifested himself in his word.
Institutes of the Christian Religion, Book 1 Chapter 10, John Calvin 1534