God isn’t complex, God is simple.
Let me explain, or better yet, let me have the Stanford Encyclopedia of Philosophy explain:
According to the classical theism of Augustine, Anselm, Aquinas and their adherents, God is radically unlike creatures in that he is devoid of any complexity or composition, whether physical or metaphysical. Besides lacking spatial and temporal parts, God is free of matter/form composition, potency/act composition, and existence/essence composition. There is also no real distinction between God as subject of his attributes and his attributes. God is thus in a sense requiring clarification identical to each of his attributes, which implies that each attribute is identical to every other one. God is omniscient, then, not in virtue of instantiating or exemplifying omniscience — which would imply a real distinction between God and the property of omniscience — but by being omniscience. And the same holds for each of the divine omni-attributes: God is what he has. As identical to each of his attributes, God is identical to his nature.
Notice, the “A-Team” believes that God has no parts, hence he is not complex, he is simple. This extends even to divine attributes, God is identical with his goodness. Good isn’t a part of God. God is identical with his omnipotence. Omnipotence isn’t a part or attribute of God. Etc.
In the Summa, Thomas Aqunias, defends this claim. He gives four reasons why God is simple, and not complex.
- God is not a body, that is God is not composed of matter. Hence God is not composite, that is God is simple.
- Every composite object is posterior to its component parts and is dependent upon them, however God is metaphysical independent.
- Every composite object has a cause. God is uncaused, thus he is not a composite object.
- Every composite has potentiality and actuality. God however is pure acutality. Hence God is simple.
Those are the four reasons why Aquinas thinks that God is simple and not complex. Divine simplicity seems to be an idea that has gone out of fashion of late. (Especially within Trinitarian debates.) Do you think its an important doctrine to hold on to? Why or why not?
CWoznicki Think Out Loud 
God IS…and we are “not yet?”
Divine simplicity is a very important concept, central to arguments that refute the possibility of there existing two necessary beings.
Is the trinity compatible with divine simplicy in any way, however?
Throughout the history of the church theologians have affirmed divine simplicity alongside of the trinity. In fact they are pretty insistent in claiming that divine simplicity is what keeps the Trinity from spiraling into tri-theism. I would highly recommend Stephen Holmes latest book: The Quest for the Trinity: The Doctrine of God in Scripture, History and Modernity, in it he addresses the modern tendency to ignore divine simplicity in discussions about the trinity, and the problems that creates.