For Donald Macleod, Jesus is ontologically sinless and so incapable of sin. Jesus’ humanity is genuine in every respect, but also utterly sinless. The human nature and flesh assumed by the eternal Son in the incarnation was a sinless human nature, sinless flesh. As such, Jesus Christ was free of both actual sin and inherent sin (Macleod, The Person of Christ Contours in Christian Theology, IVP, 1998, 221).
There was no lust. There was no affinity with sin. There was no proclivity to sin. There was no possibility of temptation from within. In no respect was he fallen and in no respect was his nature corrupt (222).
Macleod develops his own position in dialogue with, and refutation of, Edward Irving’s doctrine, whom he accuses of a Nestorian separation of the human nature from the person of Christ. He rejects Irving’s idea that in the incarnation, the Son assumed a ‘fallen’ human nature on the grounds that “it is impossible to maintain a distinction between ‘fallen’ and ‘sinful.’ Fallen Adam is sinful Adam. Fallen nature is sinful nature, dominated by ‘the flesh’ and characterized by total depravity” (228). According to Macleod, it is not enough to say that Jesus did not sin; one must go further and insist that he was unable to sin.
The crucial issue is whether Christ could have willed to sin. The answer rests entirely on his identity. He was the Son of God, ‘very God of very God’. If he sinned, God sinned. At this level, the impeccability of Christ is absolute. It rests not upon his unique endowment with the Spirit nor upon the indefectibility of God’s redemptive purpose, but upon the fact that he is who he is (229-230).
This is not to say that Jesus knew and relied on his sinlessness. Indeed, faced with temptation, he utilised every resource also available to Christians generally, in order to overcome temptation: scripture, the Holy Spirit’s presence, etc. By standing against and resisting temptation, Jesus serves as an example to all believers.
Macleod’s doctrine raises certain questions. Perhaps most importantly is his view of Jesus’ temptations which he limits to what he calls “sinless human weaknesses”: although Jesus could be tempted by such things as hunger, there was nothing within his person that could issue in temptation. If it is the case, however, that Jesus “was tempted in all things as we are, yet without sin” (Hebrews 4:15), Macleod’s proposal is too narrow, fails to do justice to the portrayal of Jesus’ temptations in scripture, and leaves us with a sense that in fact, Jesus was not really like us at all, and thus not really equipped to be the kind of faithful and sympathetic high priest that Hebrews describes.
Another concern is Macleod’s rejection of Gregory Nazianzus’s teaching that “what is not assumed is not healed.” Macleod rightly notes that this teaching arose with respect to Gregory’s rejection of Apollinarianism, but then proceeds to insist that it can have no relevance beyond that provenance. Is it actually “quite perverse to suggest that ‘the unassumed’ in this statement is ‘fallen human nature’” (224), as Macleod insists? In fact, Apollinaris’s reason for rejecting the idea that Jesus had a human mind was because the mind was “filthy,” a great source of sin.
In the end, Macleod fails to convince. In seeking to say more than what scripture says, he ends up saying less, and in so doing, diminishes the glory of the gospel and the comfort believers can gain from it.