A discussion after church today raised the question whether the possibility of sin entailed, in itself and apart from any actual evil, a diminution of goodness. The question led me to suggest that Jesus could have sinned (suggesting, if true, that perfection is not incompatible with the possibility of sin), a position which seemed in retrospect to require further consideration.
Could Jesus have sinned? One can begin by stipulating that God is incapable of sin (e.g. Hebrews 6:18, James 1:13), but even this incapacity raises some interesting questions. I cannot fly, see through walls, or live a perfect life, because something limits me–whether external constraints or internal deficiency. Obviously, such a definition of “cannot” does not apply to a perfect, omnipotent God. Perhaps the closest human analogy to the divine incapacity for sin is “will not,” rather than “cannot”?
But this raises some obvious problems as well. For even the most reliable of men, “I will not” is followed by a footnote of sorts: “…assuming no change of mind or inability of body.” Of course, one could pencil divine immutability and omnipotence into the equation, but even that doesn’t quite fit. Perhaps it’s merely our inability to escape the human connotations of the word “will,” but “God will not sin” doesn’t seem adequate; it carries just a hint of a God who merely chose the good. The statement simply isn’t strong enough to describe the God who provides not merely the prescriptive but the ontological ground of goodness.
The answer, so far as we can comprehend it, seems to lie in a combination of the ideas of “cannot” and “will not.” God cannot do anything but good, and will not do anything but good, because He is good. The divine “cannot” is really the perfect inverse of human incapacity; while a man “cannot” because He is subject to limitations which constrain the operation of his will, God “cannot” precisely because He is subject to no such limitations. God cannot sin in much the same way that I cannot like okra; it’s not in him to do it. Combine immutability, moral perfection, and omnipotence, and “will not sin” and “cannot sin” suddenly become essentially the same thing.
But back to the original question: What light does God’s incapacity for sin throw upon the question of whether Jesus could have sinned? Being fully God, it seems to follow that Jesus could not have sinned, in one sense. However, there seems to be another sense in which we must say that Jesus could have sinned.
The difficulty in considering this question is really inherent in any counterfactual concerning God. We evaluate a counterfactual by imagining a possible world in which the given facts actually pertain, but there is no possible world in which God is other than He is in reality. We might call it transworld immutability: an ontologically necessary and unchanging First Cause will look exactly the same across an infinite array of possible worlds. There is no possible world in which God does not exist, no possible world in which God is not loving, and no possible world in which Jesus sins.
Jesus could not have sinned because Jesus was fully God, and God cannot sin. QED. Yet, on the other hand, Jesus had the capacity to sin.
Consider a similar question: Could God destroy every living thing on earth with a worldwide flood? Well, yes. And no. He has the capacity to do so, a capacity rather convincingly demonstrated some thousands of years ago. But on the other hand, “all flesh shall never again be cut off by the water of the flood, neither shall there again be a flood to destroy the earth” (Genesis 9:11). And “it is impossible for God to lie” (Hebrews 6:18, cf Titus 1:2, Numbers 23:19). So God could destroy all life with a flood, and He couldn’t. One might say He could but He won’t, except that, as noted earlier, that’s simply another way of saying He could but He couldn’t. (A paradox but not a contradiction, since He could in one sense but couldn’t in another.)
It seems the question of Jesus’ ability to sin leaves us with a similar paradox. The ability to sin comes with the ability to will; to love. Jesus had such an ability. He had the capacity to sin in the same way that God has the capacity to generate a second flood. When Jesus was tempted in Matthew 4, He had the capacity to turn stones into bread, to hurl himself from the temple pinnacle, and to bow before Satan. But in the same breath we must affirm that He could not, for God cannot sin.
This appears problematic only because we are used to thinking in human terms. For any creature not simultaneously all-powerful and unchanging, capacity equals possibility. Our variability of will and susceptibility to outside forces means that any potential may turn into reality. As a result, linguistic imprecision links the concepts of capability and possibility together under an umbrella of “what could be,” and habit makes it hard for us to distinguish between the overlapping meanings.
For an immutable and all-powerful God, on the other hand, possibility does not necessarily follow from capacity. “Could” when applied to God means two very different things. Even though Jesus possessed the capacity to sin, his unchanging perfection means sin is also forever, always, and absolutely impossible for the Son of God.