Is God most simple and free from all composition? We affirm against Socinus and Vorstius
I. The Socinians agitate this controversy with us since they deny that simplicity can be attributed to God according to the Scriptures and think it should be expunged from the number of the divine attributes for no other purpose than to weaken more easily the mystery of the Trinity by establishing the composition of the divine essence (The Racovian Catechism 3.1 , p. 33). Vorstius retained this error (with various others also) and introduced it into his Tractatus theologicus de Deo (1610) and in the notes to “Disputatione III: De Natura Dei” (cf. Tractatus theologicus de Deo , pp. 19–28). With these the Remonstrants also agree. In their Apology, they deny that the simplicity of God is necessary to be believed or that anything occurs in Scripture relative to it, but that the whole doctrine is metaphysical whether you consider the word or the thing (“Apologia pro confessione sive declaratione … Remonstrantes,” 2 in Episcopius, Operum theologicorum , Pt. II, p. 129). But the orthodox have constantly taught that the essence of God is perfectly simple and free from all composition.
II. Simple is used in two senses: either absolutely and simply; or relatively and comparatively. Absolutely is such as in every kind of being excludes composition; comparatively is such as excludes it only with respect to some. Heaven and the elements are called simple bodies with respect to mixed, but do not exclude composition from their matter and form and quantitative parts. Angels and souls are simple with respect to bodies, but not absolutely such because they always involve a composition. Here we speak of absolute and not of comparative simplicity.
III. The simplicity of God considered not morally, but physically, is his incommunicable attribute by which the divine nature is conceived by us not only as free from all composition and division, but also as incapable of composition and divisibility.
Proof that God is perfectly simple.
IV. This is proved to be a property of God: (1) from his independence, because composition is of the formal reason of a being originated and dependent (since nothing can be composed by itself, but whatever is composed must necessarily be composed by another; now God is the first and independent being, recognizing no other prior to himself); (2) from his unity, because he who is absolutely one, is also absolutely simple and therefore can neither be divided nor composed; (3) from his perfection, because composition implies imperfection inasmuch as it supposes passive power, dependency and mutability; (4) from his activity, because God is a most pure act having no passive admixture and therefore rejecting all composition (because in God there is nothing which needs to be made perfect or can receive perfection from any other, but he is whatever can be and cannot be other than what he is). Whence he is usually described not only by concrete but also by abstract names—life, light, truth, etc.
V. From the removal of all species of composition (such as physical—of matter and form, since he is incorporeal); or of quantitative parts (which do not apply to God); or of subject and accident (because no accident can make the most perfect still more perfect); logical (of kind and difference because God is above every genus, nor is his a common nature capable of being restricted by difference); metaphysical act and power (since he is a pure act and incapable of change properly so called, to whom nothing new can happen or be received by him); of essence and existence (as in created things in which the nature of existence differs from that of essence, since their essence can be conceived without existence; nor does existence enter into their definition because they can be and not be, and existence with respect to them is something contingent, not necessary. For in God essence cannot be conceived without existence, and it is repugnant to conceive of God as not existing; hence philosophers call him a being by essence (i.e., which exists in virtue of its own essence) and of the nature of whose essence it is that he always exists. For this reason, God calls himself Jehovah (viz., he who is, “I am that I am” [‘hyh ‘shr ‘hyh]) to signify that being belongs to him in a far different manner than to all created things, not participatively and contingently, but necessarily, properly and independently. Finally, his simplicity is proved from nature and subsistence; for persons and essence are not related as real component extremes from which a tertium quid may arise (as in human things from the nature of man and the subsistence of Peter arises that person whom we call Peter); otherwise not a Trinity but a certain quaternity would be conceived of in God; nor do modes (such as subsistences) compose, they only modify.
VI. But as God rejects all composition in himself, so his simplicity hinders him also from being compounded with any created things so as to hold the relation of some part either of matter or form (against the opinion of the Platonists who supposed God to be the soul of the world; and of the Manicheans who held that all creatures were propagated from the essence of God). This is so both because he is altogether diverse from creatures, and because he is immutable and incorruptible (he cannot coalesce in one with any mutable and corruptible created thing). For all composition infers mutation by which a thing becomes part of a whole, which it was not before.
Sources of explanation.
VII. If all things are said to be of God (Rom. 11:36), this must be understood not hylikōs (“belonging to matter”) and materially, but dēmiourgikōs (“formatively”) and efficiently. We are called the race and offspring of God (Acts 17:28), not by a participation of the same essence, but by similarity of likeness; efficiently not essentially, as also he is called the “Father of spirits” (Heb. 12:9) with reference to creation, not to composition. The Son of God is God-man (theanthrōpos) not by composition properly so-called, but by hypostatical union (by which the Word [logos] indeed assumed human nature in one hypostasis, but was not compounded with it as part with part; but stood to it in the relation of perfecter and sustainer to make perfect and sustain an essential adjunct, so that the human nature indeed did thence receive perfection, but nothing was added by it to the divine nature).
VIII. Composition is in that in which there is more than one real entity, but not where there is only more than one mode because modes only modify and characterize, but do not compose the essence. But in divine things there are one essence and three hypostases (which are modes distinguishing indeed the persons from each other, but not composing because they are not real entities concurring to the composition of some fourth thing, since they have one common essence; but they are only modifications according to which the essence is conceived to subsist in three persons).
IX. Simplicity and triplicity are so mutually opposed that they cannot subsist at the same time (but not simplicity and Trinity because they are said in different respects): simplicity in respect to essence, but Trinity in respect to persons. In this sense, nothing hinders God (who is one in essence) from being three persons.
X. The decrees of God can be regarded in two ways: either subjectively (if it is right so to speak, i.e., on the part of the internal act in itself and absolutely); or objectively, extrinsically and relatively with respect to creatures (respectively). In the former manner, they do not differ from God himself and are no other than God himself decreeing. But in the latter, they do differ because they may be conceived as many and various (not as to the thing, since God has decreed all things by one single and most simple act, but as to the objects), even as the knowledge of God is conversant with innumerable objects without detriment to his unity.
XI. The decrees of God are free, not absolutely and as to the principle, but relatively and objectively and as to the end. For there could be no external object necessarily terminating to the divine will, for God stands in need of nothing out of himself. Therefore they could be and not be. But this does not hinder them from being called necessary as to the principle and internal act because the act of intelligence and will could not be absent from God at all. He could not be God without intelligence and will. They are necessary, therefore, as to internal existence, but free as to external relation (schesin) and habit. Nor can the will of God be said to cease absolutely, but with respect to the external object on which it is terminated.
XII. The decrees of God are immanent acts of the divine will, but not properly its effect. God ought not to be called so much the cause as the principle of them. Hence there is no need that they should be posterior to God except in our order and in the manner of conceiving them.
XIII. Although the essence of God (considered simply in itself) is absolute and implies no relation to creatures, yet this does not hinder it (when considered with relative opposition to creatures and as determining itself in the manner of vital principle to the production of this or that thing out of itself) from having a certain reference (schesin) and relation to creatures. Nor can that manifold relation make composition in God, more than the relation which his omniscience and omnipotence bear to things ad extra, constituted a real difference between God and his omnipotence and omniscience.
XIV. Whatever in God is essential and absolute is God himself. Thus the absolute attributes may be identified really with the divine essence and are in it essentially, not accidentally. If they are predicated of God in the concrete, their subject is only of denomination, not of inhesion (inhaesionis). But whatever is personal and modal in God is indeed God himself in the concrete, though not in the abstract.
XV. The relative attributes do not argue composition, but distinction. The formal nature of relations is not to be in, but to be to. Nor do they superadd a new perfection to the essence, but only imply a habitude of the essence to other things. Paternity and dominion do not render him another being, but in a different manner dispose the possessor without superinducing a change in him.
XVI. The personal property of the Son does not make his essence different from that of the Father, nor of a simple essence make a composed, for nothing real is added to the essence, rather it only makes the Son distinct from the Father. Distinction is not composition.
XVII. The fathers often insist on this simplicity of God. “The nature of God is simple and immutable and undisturbed, nor is he himself one thing and what he is and has another thing” (Augustine, 1. 5, de Trinit. c. 1+). And after teaching that no creature is truly and perfectly simple, he adds: “Now although God may be called manifold, yet he is truly perfectly simple, for he is called great, wise, happy, and true, and whatever with propriety may be said of him. But his greatness is the same as his wisdom, for he is not great in mass, but in virtue, and his goodness is the same as his wisdom and greatness and truth” (The Trinity 6.6, 7* [FC 45:208–9; PL 42.929]). So too Athanasius: “God is not composed who composed all things that they might be; nor is he such as those things are which were made by his word; since he is a simple substance in whom there is no quality nor any shadow of change, as James testifies” (To the Bishops of Africa 8 [NPNF2, 4:493; PG 26.1043]).
—Francis Turretin, Institutes of Elenctic Theology, trans. George Musgrave Giger, ed. James T. Dennison Jr., vol. 1 (Phillipsburg, NJ: P&R Publishing, 1992–1997), 3.7 [191–94].