I was recently asked at Speaker's Corner in Hyde Park about whether Christ has two wills or just one will. One must of course always be careful when talking about the nature of God, since -- according to both the Bible and the Qur'an (Surah 42:11, 112:4) -- God is not like any created thing and thus analogies and comparisons to things in creation are notoriously problematic.
We have no experience of any single person possessing two natures, and so have little idea of what exactly that would entail. Nonetheless, Scripture affirms that the person of Christ has two natures. He is fully human and yet fully deity. In the person of Christ, the fullness of the divine essence has been poured into a physical body (Colossians 2:9).
I believe that, in one sense, Jesus could be said to have two wills; in another sense, Jesus could be said to have only one will. If by saying that Jesus possesses two distinct wills you mean that He possesses two separate centers of consciousness which conflict in their intentions and will, then such a view collapses into Nestorianism, a well known fifth century heresy which maintains that Jesus is two persons. At Speaker's Corner, Muslim polemicist Mansoor Ahmed asked me whether the human will of Jesus worships the divine will of Jesus. Thus, it was clear to me that by saying that Jesus possesses two wills, Mansoor meant it in the heretical Nestorian sense. In this sense, Jesus only possesses a single will. Yes, he most definitely possesses two natures. But to suggest that Jesus has two separate and conflicting wills seems to me to be virtually indistinguishable from Nestorianism.
In another sense, however, Jesus can be said to have two wills. This is clearly seen, for instance, at Jesus' temptation (Matthew 4, Mark 1, Luke 4), in which Jesus, according to Hebrews 4 "in every respect has been tempted as we are, yet without sin." One might ask, if I am saying that Jesus possesses only one will, then how can He have been tempted? After all, God cannot sin. In response to this, I would point out that even a single person can have a complexity of will. For example, a sailor drifting at sea might desire to drink the sea water in order to quench his thirst, and yet at the same time know that drinking the salt water will only worsen his thirst. In a similar way, Christ -- being fully and completely human -- possessed human desires, such as the desire to not be hungry. At the same time, however, he knew that it would be sinful for him to turn the stones into bread as the Devil has tempted him to do, and so he did not succumb to the temptation. Thus, insofar as it is possible for a single person to possess a complexity of will, Jesus possessed a complexity of will.
It was in His human nature that Christ bore the temptation to sin. I believe that the divine nature of Christ would always have served as a backstop to prevent Christ from sinning. Nonetheless, Christ bore the temptation in the arm of His flesh and overcame.
Jesus demonstrates that His will is perfectly congruent and in alignment with the will of the Father. In John 10:30, He asserts that "I and the Father are one". Given the context, it is apparent that He is speaking of a oneness of purpose or will in bringing about the salvation of God's people. It is certainly true to say that Christ had a human mind. Nonetheless, His will was always to be about His Father's business (Luke 2:49).
Likewise, in the garden of Gethsemane, Jesus in His human nature had the desire to not experience pain or abandonment and separation from the favorable presence of God, for "it is a fearful thing to fall into the hands of the living God" (Hebrews 10:31). And He knew very well what experiencing the wrath of God would entail. Hence, in Matthew 26:39 / Mark 14:36, Jesus says "My Father, if it be possible, let this cup pass from me; nevertheless, not as I will, but as you will." While, since He possessed a human nature, He felt the human desire to not experience pain, He nonetheless understood full well that experiencing the wrath of God would be necessary in order to provide redemption for His people.
In summary, the idea that Christ has two wills, I believe to be in error in any sense that suggests that Christ possesses two separate centers of consciousness (Nestorianism). On the other hand, I believe it is quite valid to assert that Christ possessed a complexity of will in the manner in which individual persons can be said to possess a complexity of will.