People who say that Christ could have sinned usually claim that an impeccably holy Christ could not actually have suffered when tempted by Satan or sinful people. To really suffer in the face of temptation, they say, you must be able to sin. Although this view may sound superficially appealing, it is actually the very opposite of the truth. The actual fact is that the holier the being, the greater the suffering when tempted. When Eve was tempted by Satan in the Garden of Eden, she suffered very little during the temptation, for the twofold reason that she did not understand the seriousness of sin and she quickly yielded to the temptation.
Christ, on the other hand, suffered infinitely when tempted by Satan in the wilderness, for the twofold reason that He understood fully the awful nature of sin and He never yielded to the temptation. The same contrast could be made between Adam’s temptation in the Garden by a human (Eve) and Christ’s temptation in the world by the people who hated Him: Adam suffered very little in the face of his temptation, whereas Christ suffered infinitely. That is why Hebrews 2:18 tells us, “He himself suffered when he was tempted.”
The purpose of Christ’s temptation in the wilderness was not for God to find out whether Christ might sin, but for God to demonstrate to the intelligent universe—angels, demons, and humans— that Christ was impeccably holy, no matter how cleverly tempted by Satan, and that He was therefore magnificently qualified to be the holy Savior of sinful people.