Jesus was completely without sin according to the Bible. Paul writes, “He made Him who knew no sin to be sin on our behalf, that we might become the righteousness of God in Him” (2 Cor. 5:21). The author of Hebrews writes, “We do not have a high priest who cannot sympathize with our weaknesses, but One who has been tempted in all things as we are, yet without sin” (Heb. 4:15). John writes, “You know that He appeared in order to take away sins; and in Him there is no sin” (1 Jn. 3:5). Jesus even had the audacity to ask, “Which one of you convicts Me of sin?” (Jn. 8:46) Which one of us could ask such a question!
Jesus had to be without sin in order to pay for the sin of others (Heb. 7:26; 9:14; 1 Pet. 2:22; Jn. 8:46; 8:29; 15:10). This is also called the “impeccability” of Jesus.
Could Jesus fall into temptation?
Theologians debate this question. The Reformed syllogism looks like this:
(1) God can’t be tempted (Jas 1:13).
(2) Jesus is God (Col 2:9).
(3) Therefore, Jesus could not sin (impeccability).
However, Jesus was also human, and humans can be tempted. Jesus was tempted (Mt. 4:1) like we are (Heb. 2:18; 4:15-16), yet without sin. These biblical accounts strongly imply that these temptations were real in the sense that Jesus could have fallen to them. Moreover, other sinless beings (e.g. Adam, Eve, Satan, angels) were originally sinless, but fell into sin. Does this mean that Jesus could have sinned?
Scripture does not answer this question directly. However, it infers that Jesus did not have a sin-nature. Thus he could not have sinned. In Romans 8:3, Paul stops short of affirming that Jesus had “sinful flesh?” and instead says Jesus “came in the likeness of sinful flesh.” While Adam and his offspring were born under condemnation, this certainly wasn’t true of Jesus (Rom. 5:12-19).
Does this mean that Jesus was never tempted?
Some might think that this means that Jesus didn’t struggle with sin, if it was impossible for him to sin. However, this is not the case. He struggled with temptation (Heb. 4:15; Mt. 4:1)—even if he couldn’t have acted on it. Philosopher Paul Copan illustrates:
The incarnate Son’s temptations were real; acting on them seemed a genuine possibility to Him. Though unique, His situation is conceivable: Imagine entering a room and closing the door behind you. Unbeknown to you, the door has an automatic two-hour time lock. You consider leaving once or twice, but you freely decide to read for the full two hours, after which you leave the room. Would you have been able to leave earlier? No. But why did you stay in and not try to go out? Because you freely decided to stay. Similarly, Christ freely chose, in submission to the Spirit, to resist temptation even though it was impossible for Him to sin; however, His divine awareness didn’t overwhelm or impose itself on His human awareness.
Moreover, only those who successfully resist temptation feel its full weight. For instance, consider the alcoholic who says, “I can quit any time I want!” They haven’t really felt the force of temptation, until their resist their temptation.
Additionally, Jesus was no doubt placed under a higher degree of temptation, because of the gravity of his mission and the spiritual attack which accompanied it. None of us have had this level of temptation or attack.
 The view that Christ could have sinned is known as peccability (Latin: potuit non peccare, “able not to sin,”) while the view that Christ could not have sinned is called impeccability (Latin: non potuit peccare, “not able to sin”). See an argument for impeccability in Louis Berkhof, Systematic Theology (Grand Rapids: Eerdmans, 1941), p. 318.
 Copan, Paul, and William Lane Craig. Contending with Christianity’s Critics: Answering New Atheists & Other Objectors. Nashville: B & H Academic, 2009. 228.
 Millard Erickson wrote, “The person who resists knows the full force of temptation. Sinlessness points to a more intense rather than less intense temptation.” Erickson, Millard J. Christian Theology. Grand Rapids, MI: Baker Book House, 1983.