R.C Sproul the editor of the Reformation Study Bible explains this further saying,

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Was Christ capable of sinning?

Did Jesus have the ability to sin? The problem in that question is that if Jesus did have the ability to sin, does that mean he had original sin and participated in a fallen nature? If that were the case, he wouldn’t even be qualified to save himself, let alone us. If he did not have the ability to sin, was his temptation (so central to God’s giving him the crown of glory for his obedience) just a charade -- was he really not subjected to real temptation?

The New Testament tells us that Jesus was like us at every point save one: He was without sin. It tells us that Jesus became incarnate and took upon himself human nature. It also tells us that he is the second Adam. Generally, classical Christology teaches that when Jesus was incarnate and became the new Adam, he came born with the same nature Adam had before the Fall. Adam didn’t have original sin when he was created. So Jesus did not have original sin. So we would ask the same question: Was Adam capable of sinning? Yes, he was. Christ, the second Adam, was also capable of sinning in the sense that he had all of the faculties and all of the equipment to sin if that’s what he chose to do.

Could Jesus have sinned if he had wanted to? Absolutely. Of course, he didn’t want to. So if you ask it a different way, could Jesus sin if he didn’t want to? No, he couldn’t sin if he didn’t want to any more than God could sin because God doesn’t want to sin. Wanting to sin is a prerequisite for sinning.

But then we have to push it one step further: Could Jesus have wanted to sin? Theologians are divided on this point. I would say yes, I think he could have. I think that’s part of being made after the likeness of Adam. When we’re in heaven and are totally glorified, then we will no longer have the power and ability to sin. That’s what we look forward to; that’s what Jesus earned for himself and for us through his perfect obedience. Christ’s perfect obedience was not a charade. He actually was victorious over every conceivable temptation that was thrown his way.

Page 45-46
Now, That’s A Good Question
By R. C. Sproul

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The happy result for us is that because ‘He Himself has suffered, being tempted, He is able to aid those who are tempted’ (Heb. 2:18)”. Note, the first line, “Jesus could not sin, but He was able to be tempted”, the peccability people want to say, “Jesus had the ability to sin”, instead of He had the ability to be tempted. With the word “tempted”, there are many ways to interpret depending on your bent (Heb. 2:18, Heb.4:15) as I tried to show to Kyle, by giving him an exegesis from another web site.
Where DOES the first line of Scripture and not a mere Study Bible say Jesus could not sin? They have added words to the holy text. The text says, "He suffered." How did Christ suffer? He was tempted. Was His temptation genuine? YES, then He was capable of sin.

As far as the word tempted there are not many ways it can be used here in this verse. In context the tempted is speaking concerning our infirmities. What are these infirmities and where did they lead? Verse 16 specifically speaks of mere man's incapability and the need for grace. Read chapter 3 of Hebrews and look at the references to unbelief, the hardness of sin, the grieving of the Holy Spirit, etc. etc., etc. Look at Heb 2:17-18. Christ is the High Priest--compare with Hebrews 5.

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Jesus is not only fully divine; he is also fully human and thus understands our weaknesses and our temptations. Furthermore, Jesus himself experienced weaknesses and temptations. At the onset of his ministry, he was tempted by Satan; he coped with thirst, weariness, desertion, and disappointments throughout his earthly ministry.

Jesus, fully acquainted with human nature, is “touched with the feeling of our weaknesses,” as B. F. Westcott puts it; He has been tempted—in extent and range—in every way. Nothing in human experience is foreign to him, for he himself has endured it. And he has been tempted just as intensely as we are. The author adds the qualifying phrase yet was without sin.

When he was in the wilderness, Jesus experienced hunger, and the devil tempted him by asking him to make bread out of stones (Matt. 4:2–3). While hanging on the cross, he was mocked by chief priests, teachers of the law, and elders, who said, “Let him come down now from the cross … for he said, ‘I am the Son of God’ ” (Matt. 27:42, 43). He endured the full range of temptations, although, as the writer notes, without sinning. Sin is the only human experience in which Christ has no part.

Kistemaker, Simon J., and William Hendriksen. Vol. 15, New Testament Commentary : Exposition of Hebrews. Accompanying biblical text is author's translation. New Testament Commentary, Page 125. Grand Rapids: Baker Book House, 1953-2001.

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