The best theologians, past and present, have been divided on the question of whether Jesus could have sinned. I believe that since Jesus was fully human, it was possible for him to sin. Obviously, the divine nature cannot sin. But if Christ’s divine nature prevented him from sinning, in what sense did he obey the law of God as the second Adam? At his birth, Jesus’ human nature was exactly the same as Adam’s before the fall, with respect to his moral capabilities. Jesus had what Augustine called the posse peccare and the posse non peccare, that is, the ability to sin and the ability not to sin. Adam sinned; Jesus did not. Satan did everything in his power to corrupt Jesus and tempt him to sin. That would have been an exercise in futility had he been trying to tempt a divine person to sin. Satan was not trying to get God to sin. He was trying to get the human nature of Christ to sin, so that he would not be qualified to be the Savior.
At the same time, Christ was uniquely sanctified and ministered to by the Holy Spirit. In order to sin, a person must have a desire for sin. But Jesus’ human nature throughout his life was marked by a zeal for righteousness. “My food is to do the will of Him who sent Me” (John 4:34), he said. As long as Jesus had no desire to sin, he would not sin. I may be wrong, but I think it is wrong to believe that Christ’s divine nature made it impossible for his human nature to sin. If that were the case, the temptation, the tests, and his assuming of the responsibility of the first Adam would have all been charades. This position protects the integrity of the authenticity of the human nature because it was the human nature that carried out the mission of the second Adam on our behalf. It was the human nature uniquely anointed beyond measure by the Holy Spirit.
(Excerpt from R.C. Sproul’s, Truths We Confess: A Layman’s Guide to the Westminster Confession of Faith (Volume 1) via Ligonier Blog)
I think it is wrong to believe that Christ’s divine nature made it impossible for his human nature to sin. —R.C. SproulSo what? Does this even matter? Yes, it matters a lot and I agree with RC here. Jesus didn’t beam in to the earth. He didn’t suddenly appear in the clouds. He wasn’t sheltered in a temple from the time of his appearing. Jesus was born of a woman. He had parents who changed his diapers and nursed him and told him that the fire would burn him if he touched it. He ate, slept, stubbed his toe and got splinters. Jesus was a human being. Fully human. 100% human without sin. He was born and he died just like we are born and we die. But unlike us, Jesus was the eternally existing Son of God. In Colossians Paul tells us that he is the image of the invisible God, the exact representation of God.
It seems to me that Jesus’ human nature, being truly human, could be tempted to sin. Yet, since he lacked inherited guilt, he remained free to chose not to sin. Since his human and divine natures are perfectly united in him, his divine nature would have constrained his humanity to not sin in this way: Jesus’ human nature would be doing what humanity should do; depend upon God for strength in the face of temptation. Could he have sinned? Not if he was doing what a perfect human would do by trusting in God. Was he truly tempted to sin? Yes, his human nature, being what it is was was weak in relation to temptation but was strong in the power of the Lord.
This stuff matters because Jesus is a sympathetic God and savior. He isn’t aloof from our struggles and difficulties.