It is impossible for God to lie (Hebrews 6:18). We have been reading through Anselm’s Cur Deus Homo for LHC book club, and in it he wrestles with the issue that there are things God does not/cannot do and is still perfect and worthy of praise. The specific issue in his work is the fact that God “cannot” lie – not, does not or will not, but cannot. How can it be that there is something (maybe several things?) God cannot do, and yet remain perfect in his being – omniscient, omnipotent, etc.?
Using lying as the example, here are couple of thoughts about answering this question. (Below, I only speak of lying in the derogatory sense of “deliberate misguidance” and not the more delicate notions of lies that have good consequences, lies of ignorance, or any other shade of the act of lying.)
There are some capacities we gain or dispositions we develop through life that make us better people – we are greater because of them. When we learn how to perform certain mathematical functions, or learn that knowledge is better than deliberate ignorance, or we learn that sharing is better than selfishness, we become better and more capable people because of them. Then there are capacities or dispositions that take the exact opposite course in the maturing life. Infants are inherently selfish, so as we lose that disposition, we mature. So understood, the capacity or disposition to lie falls into the second category. Our ability to lie and God’s inability to lie make us less mature and him perfectly mature.
The disposition or capacity to lie does not make a character better, but worse. Lying is one less disposition/capacity God has, but as such, that makes God’s nature more perfect, not less. My disposition to lie makes my character less perfect, and the greater my disposition to lie, the worse my character becomes. Part of the growth, maturity, even spiritual formation of a human includes the disposition of truth-telling becoming stronger than lying.
Hence, God’s utter inability to lie speaks to his complete perfection. God cannot lie because his character is not tainted at all with the vice of lying.
I have so far used the words “capacity” and “disposition” to describe the ability to lie, but I now want to cross “capacity” off the list and assert that only truth-telling is a capacity. Lying is a corruption of the capacity, and thus is a vicious and corrosive disposition. The virtue of truth-telling is corrupted by the degree to which I am disposed to lie.
Truth-telling and lying are not the exact opposites of the same moral coin; they are not a ying-yang of human interaction. Truth-telling is better understood as the ubiquitous and necessary requirement for all human interaction, and hence the foundational virtue. In all human interaction we rightly begin with the assumption of truth-telling unless we have a reason to believe otherwise. And using those instances in which we have reason to suspect malfeasance as examples, we can quickly see why the universal assumption of lying would be devastating to relationships. Virtues (moral goods) are logically prior to vices (moral evils) and are hence properly understood as capacities. As Augustine put it, moral evils are only privations of the good, and hence are only corrosive dispositions and not capacities.
In addition, God freely cannot lie. When presented with the idea that it is “impossible” for God to lie, we are tempted to think that God is out of luck with his own free will, and thus is not free with regard to lying and truth-telling. But, in the context set so far, God’s virtue of truth-telling is perfect and he is complete in his freedom to not lie.
There is no external force outside of God that coerces him to always tell the truth and never lie, thus making his truth-telling some kind of nefarious necessity. But instead of arguing along the lines of external causes, we see in our construal so far that God is, within his own character, perfect with regard to truth-telling.
Imagine your progression from more lying to more truth-telling as your character improves. Let us say that you have set the personal and spiritual goal of becoming more Christ-like, and through the exercise of the spiritual disciplines and the work of the Holy Spirit in your life, your desire to lie in any and every situation diminishes over time. With each step along the way, you are still able to lie all you want to, which increasingly is less and less. You lie less not primarily because you are less free to lie, but because you are more free and more willing to use your freedom to tell the truth. Taken to a logical extreme, you can imagine a point at which you will not lie (it will become “impossible” for you to lie) exactly because your freedom and willingness to tell the truth becomes complete. And though, arguably, no human on earth will reach that point of virtuous perfection, God stands as the model of that very thing.
So how is it that it is impossible for God to do something like lie, and still be perfect in his being? It is because certain dispositions are a detriment to a virtuous character and for God not to have those is in fact proof of his perfect and magnificent being.