Could Jesus have sinned? This is a most difficult question. If Jesus could not sin, was he really “tempted as we are” (Heb 4:15)? His human nature was indeed tempted to sin but he never did. Had he sinned, he could not atone for our sins. Grudem, in chapter 26 [1] of his Systematic Theology [2] reminds us that the scriptures go only so far on this issue and we must take care in formulating our answer. We must affirm that Jesus was tempted and that God cannot be tempted (James 1:13). Any answer to this question must be honest to both of these truths.
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 choose 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. This is not a conflict within the persons or the wills of Jesus, this is Jesus human nature doing what humanity should do: depend upon God for strength in the face of temptation. Could he have sinned? No, he was doing what a perfect human would do: 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.