Given the recent widespread confusion about the doctrine of God among Reformed theologians, we thought it would be helpful to post some excerpts on the basic concepts of theology proper from Zacharias Ursinus. Ursinus gives a scholastic treatment of the question, one that is both traditional and succinct. The following comes from his Commentary on the Heidelberg Catechism, eighth Lord’s Day section 3, pg. 128-129 of the P&R edition. It introduces the basic concept of monotheism, a starting affirmation for all Christian theology. ~ed.
The unity of God is proven, in the first place, by the express testimony of Scripture. “Hear, Israel, the Lord our God, is one God.” “See now that I, even I, am he, and there is no God with me.” “I am the First and the Last, and beside me there is no God.” “We know that an idol is nothing in the world, and that there is none other God but one.” “There is one God, and one Mediator between God and man, the man Christ Jesus.” (Deut. 6:4; 32:39. Is. 44:6. 1 Cor. 8:4. 1 Tim. 2:5.) See also Deut. 4:35, Ps. 18:31, Is. 37:16; 45:21, Hosea 13:4, Mal 2:10, Mark 12:32, Rom. 3:20, Gal. 3:20., &c.
Secondly the unity of God may be proven by many solid arguments, such as the following:
He who alone reigns over all, and governs all things in the same way, and so possesses supreme power and majesty, cannot be more than one. But there is no one, beside God, who is so supreme and great, that no greater can either exist or be conceived of. Therefore, he is God alone, and beside him there can be no other God. “I am the Lord; that is my name, and my glory will I not give to another.” “Now unto the King eternal, immortal, invisible, the only wise God,” &c. “Thou art worthy, Lord, to receive glory, and honor, and power, for thou hast created all things.” (Is. 42:8, 1 Tim. 1:17, Rev. 4: 11.)
He who is perfect in the highest degree, can be only one; for he who alone has the whole and every part is absolutely perfect. God, now, is thus perfect, because he is the cause of all that is good in nature. Therefore, nothing is more absurd, than to suppose any one to be God, who is not supreme and perfect, in the highest degree. “Lord, who is likeunto thee?” (Ps. 89: 8.)
There cannot be more than one being that is omnipotent, for if there were many, they would mutually hinder and oppose each other, and so would not be omnipotent. It is by this argument that the monarchy of the world is ascribed to one God in the prophecy of Daniel, where it is said, “No one can stay his hand, or resist his will.” (Dan. 4: 35.)
If we suppose many Gods to exist, no one of them would be able singly and alone, to rule all the rest, and so all would be imperfect, and not Gods; or else the rest would be at ease and superfluous. But it is absurd to suppose that God is such an one as has not sufficient power to govern all things, or who is at ease and superfluous. Therefore, there is, necessarily, but one God, who alone is sufficient for all things.
There cannot be more than one being that is infinite, or immense; for if there were more than one, no one would be everywhere. Hence, there cannot be many Gods, but only one God, who alone is infinite.
There can be but one first cause of all things. God is that first cause. Therefore, he is one God, excluding all others.
The highest good can be only one; for if there were besides this also another highest good, it would either be greater or less, or equal to the first. But if it were greater, the first would not be the highest, and yet it would be God, which would be reproachful to the Deity; if it were less, then this would not be the highest good, and so would not be God; and if it were equal, then neither would be the highest good, nor God.
The use, or benefit, of this question is, that seeing there is but one God, we must not worship or adore any one beside him; neither must we look any where else than to this one God for all good things; and be thankful to him alone for what we have received.
Obj. But the Scriptures declare that there are many gods: “I have said, ye are gods.” “There are gods many, and lords many.” (Ps. 82:6. 1 Cor. 8:5.) Moses is also said to have been made a god to Pharaoh. (Ex. 7:1.) Yea, the devil is called the god of this world. (2 Cor. 4 : 4.) Ans. The word God is used in a double sense. Sometimes it signifies him who is God by nature, and has his being from none, but of and from himself. Such a Being is the living and true God. Then again it designates one who bears some resemblance to the true God in dignity, office, &c. Such persons are, 1. Magistrates and judges, who are called gods on account of their dignity, and the office which they bear in the name of God, as it is said, “By me kings reign.” (Prov. 8:15.) As God, therefore, administers his government through magistrates and judges, as his vicegerents and servants upon the earth, he in like manner bestows upon them the honor of his own name by calling them gods, that those under them may know that they have to deal with God himself, whether they obey or resist the magistrate, according as it is said, ” Whosoever resisteth the power, rcsisteth the ordinance of God.” (Rom. 13 : 2.) 2. Angels are also called gods, in view of the dignity and excellency of their nature, power and wisdom, in which they greatly excel other creatures; and on account of the office which they exercise by divine appointment in defending the godly and punishing the wicked. “Thou hast made him a little lower than the gods,” that is, the angels. “Are they not all ministering spirits.” (Ps. 8:5. Heb. 1:14.) 3. The devil is called the god of this world, on account of the great power which he has over men, and other creatures, according to the just judgment of God. 4. There are many things which are called gods, in the opinion of men, who regard and worship certain things and creatures for gods. So idols are called gods, by imitation. “The gods that have not made the heavens and the earth, even they shall perish from the earth, and from under these heavens.” “Whose god is their belly.” (Jer. 10:11. Phil. 3:19.) But here the question is in reference to the true God — to him who is God by nature, having his power from no one else, but from and by himself. Such a being is one only.