“This is the ultimate in human knowledge of God: to know that we do not know Him"
St. Thomas said: “This is the ultimate in human knowledge of God: to know that we do not know Him” (Questiones Disputatiae de Potentia Dei, 7, 5, ad 14). According to this way, we use words like “infinite,” “incorporeal, ”immutable,” and “ineffable” to describe God. Even to call God “perfect,” says St. Thomas, we do by way of negation, because we understand perfection as “lacking nothing.”
This way helps us guard against the presumption of thinking that through human insight we can penetrate the impenetrable mystery of God. St. Augustine said that “If you comprehend, it is not God. If you are able to comprehend, it is because you mistook something else for God. If you almost comprehend, it is again because you allowed your own thoughts to deceive you” (Sermon 52, 16; see also Sermon 117, 5).
We should be careful to distinguish, though, between God himself and this way of speaking about him. We should never start thinking that God himself is negative in any way. On the contrary, he is the fullness of being and in him there is “no privation,” according to St. Thomas; it is only “according to the mode of our apprehension” that “He is known to us by way of privation and remotion” (ST I.11.3.ad2). This is in contrast to the teaching of some who tend toward negating God’s very existence. For example, John Scot Erigena (9th century) wrote: "We do not know what God is. God Himself does not know what He is because He is not anything. Literally God is not, because He transcends being." This statement is in complete opposition to Catholic theology and a Catholic understanding of the via negativa. The Catholic understanding is much better summed up by early Christian writer Tertullian: “That which is infinite is known only to itself. This it is which gives some notion of God, while yet beyond all our conceptions—our very incapacity of fully grasping Him affords us the idea of what He really is. He is presented to our minds in His transcendent greatness, as at once known and unknown” (Apologeticus, 17).
The value of the via negativa does not mean, however, that we should on the other hand predicate nothing of God. Christianity is founded on the revelation of God, who has chosen to reveal something of his mystery to us. The Church has not only a via negativa but also a via positiva. A look at the Catholic liturgy makes that quite clear: “Heavenly Father,” “Holy, Holy, Holy,” etc. The positive and negative ways of speaking about God are best set as correctives to each other, which strain toward a synthesis.