Blind rage. It’s a rather evocative phrase that gets at the heart of the passions of humanity. In polite terms, we might describe such a person as “passionate.” But, when we talk about God, we dare not describe him as “passionate.” Rather, theologians have used the term impassibility to describe God with respect to emotions.
Though the term impassibility is both a negation and an obscure Latin loan word (it sounds like the attribute of God that nobody is able to pass him on the highway), it describes something very important about God. It means that God is not able to suffer or to be manipulated by emotion. He does not change with respect to emotions, and he does not suffer loss.
Now, emotion isn’t a great word to use; it collapses a distinction between passions and affections that needs to be maintained. For the sake of clarity, affections are the positive word—and passions the negative—for emotions. Thus, when the Westminster Assembly wrote that God is “a most pure spirit, invisible, without body, parts, or passions” (WCF 2.1), they did not intend for us to think of God as emotionless, i.e. cold, calculating, and unfeeling. Rather, they intended to separate God’s affections from our passions, like blind rage. Thus, when Scripture speaks of God as a jealous God, this jealousy is a right affection and not an excessive passion. God’s jealousy is pure and full affection in the same way that God’s love is the purest and fullest expression of love.
This distinction is important for at least two reasons. First, it helps us to avoid thinking about God in the human terms of emotion. God does not capriciously pour out his wrath like humans would. God is not prone to a sudden change in his love for his chosen people. Scripture attributes affections to God in their fullest and purest sense.
Second, and related, impassibility gives us confidence that God’s promises won’t change even when his people are incorrigible. Divine impassibility assuages our fears that we will provoke God to forsaking us. God cannot be moved by emotion like that. Certainly it is true that “the LORD reproves him whom he loves, as a father the son in whom he delights” (Prov 3:12), but he will never leave or forsake us because we make him so mad.
But you may be wondering about the suffering of Christ. Doesn’t Christ’s suffering, especially on the cross, make it difficult to uphold divine impassibility? After all, Hebrews says that because Jesus “himself has suffered when tempted, he is able to help those who are being tempted” (2:18). If Jesus suffered, and Jesus is God, then didn’t God suffer? Not quite.
Though the answer to this objection draws into a discussion of the two natures of Christ, it’s worth the detour to defend God’s impassibility. With that said, we need to acknowledge that Jesus did suffer on the cross and throughout his earthly ministry. However, Jesus as God, did not suffer. Thomas Weinandy helps to draw out an important distinction related to the two natures of Christ. “If the Son of God experienced suffering in his divine nature, then it would be God suffering as God in a man. But the incarnation, which demands that the Son of God actually exists as a man and not just dwells in a man, equally demands that the Son of God suffers as a man and not just suffers in a man.” This distinction helps us to avoid denying God’s impassibility while still acknowledging the very real suffering that Christ endured.
Why does this matter? Hebrews 2 actually helps us see the importance of this distinction. In vv16-17, the writer says, “For surely it is not angels that he helps, but he helps the offspring of Abraham. Therefore, he had to be made like his brothers in every respect, so that he might become a merciful and faithful high priest in the service of God, to make propitiation for the sins of the people.”
This highlights the issue at hand. If we attribute the propiatory suffering of Jesus to his divine nature, then you and I are still lost in our sins. Matthew Barrett says, “As counterintuitive as it may seem, if Christ suffers in his deity at the cross—or the Father suffers with him as he looks on—then we have actually excluded the Son from suffering for us.” He has not suffered for us if he has not suffered as us.
Thus, God’s impassibility is an important attribute. Because he cannot be moved by emotion, his promises are secure. Because he cannot suffer loss, Christ’s sacrifice for us can be valid and complete. In the end, this obscure word says much that is important about God.
 Quoted in Matthew Barrett, None Greater: The Undomesticated Attributes of God (Grand Rapids: Baker Books, 2019), 133.
 Barrett, None Greater, 134.