I don't think that miracles…in and of themselves, prove Christ's divinity. So, if the man in the shop were to start reproducing Christ's miracles, you would in no way be constrained to admit that he was divine, and to say that is in no way to weaken the claims of Christianity.
Certainly, the miracles act as evidence in favour of Christ's divinity--the fact that miracles happened certainly testify that something out of the ordinary was happening in Christ Jesus, but of themselves they don't prove the case one way or the other. Indeed, if you look at the gospels, you will not see anyone (to the best of my recollection) recognizing Jesus Christ as God purely because of His miracles. Indeed, there are some passages where He is accused of being in league with demons because of the miracles He performs. On the basis of His miracles, Christ was recognized as a great prophet, a man especially blessed by God or even the Messiah, but there is no evidence anywhere in the Scriptures of the miracles of Christ being the primary evidence for His divinity.
The miracles make sense as part of the overall picture of Christ which leads us to conclude that he is divine, but on their own, as works of power, they do not set Christ apart from the Prophets, Saints or (dare I say it?) wonderworkers claimed by other religions.
Now, I have no doubt that Christ worked the miracles to draw attention to His power. But that is not the only reason that He worked them. Each of the miracles in the gospel were performed by Christ not simply to show that He had a more-than-natural power, but also because they revealed something about who He is. He changed the water into wine and at Cana to show that the age of the Jewish Law was passing away (the water was to be used for ritual purification) and the new messianic age (the abundance of wine) had arrived. He opened the eyes of the blind out of compassion certainly, but also to show that it was part of his mission to bring sight to the blind in a metaphorical sense too.
And this is what sets the miracles of Christ apart from the hypothetical case of our Muslim 'friend' changing water into wine. In the case of our the man in the shop, such a work it would be a mere imitation of Christ. In the context of what we know about Christ's mission, changing water into wine was a claim about who He is. Christ's miracles carry with them a level of meaning when viewed in the context of His life and mission and in the context of the society in which he performed them that their reproduction in another context does not have.
So, in summary--as acts of power Christ's miracles are not enough to convince us that Christ is God. Nor is there any evidence that based on the power of his miracles alone that people were carried away with the idea of the divinity of Christ. However, the miracles do form part of our reasons for believing that Christ is divine. In the context of 1st century Palestine, they show that Christ was making certain implicit and explicit claims about who He was--at the very least, they carry with them very strong suggestions of a particular type of Messianic power. In the context of the entire story of Christ and the early Church, they form a central part of the picture of a man whom we justly believe (by the grace of God) to be Divine. Their reproduction by someone else however, would not be sufficient to convince us of the divinity of that other person.
I think it's worth remembering that the gospels don't limit Christ's claim to divinity to his miracles. Indeed, His claim to divinity is more powerfully expressed in several other ways. In my opinion, at the core of his claim to divinity was his claim that He could forgive sins. This was one of the things that really infuriated His Jewish enemies at the time. (It's this claim to forgive sins that really strikes me--I don't think that it's the kind of thing that even a clever author who would want to exaggerate Christ's reputation would or could invent.)
His assertion of authority over the Mosaic Law (e.g regarding the Sabbath and Divorce) is also an implicit claim to divine power. No one other than the Divine Legislator would be capable of such a change to the Law. I note too that the charge brought against Christ by His enemies was one of blasphemy--they recognized His claim to divinity and rejected it as in impiety. I'm also quite fond of that scene in the Gospel of St John were Christ is apprehended in the garden and says, "I am He". Immediately, his captors fall to the ground. The reason they fall to the ground, or so the exegetes tell us, is that his saying, "I am He" is an echo of God's revelation to Moses as "I am Who I am."
Anyway, I guess what I'm saying is that the miracles just form part of the picture of the person of Jesus Christ who can only be understood as divine when we look at the bigger picture. Even if we adopt a very rationalistic reading of Scripture, I think it is obvious that Christ made some pretty extraordinary claims about Himself. In the end, we are left with the dilemma which C. S. Lewis places before us--we can't simply accept Christ as being only a good man--he is either the Son of God or a madman.
Of course, the ultimate seal on Christ's claims about himself is the Resurrection--the ultimate vindication of Him, His mission and who He claimed to be. It is when Christ rises from the dead that the sceptic Thomas makes the most heartfelt expression of Christ's divinity when he says, "my Lord and my God."
- Fr. Zadok on "Sancta Sanctis"
The Miracle Detective. By Randall Sullivan. Author and Rolling Stone journalist Randall Sullivan's personal experiences of the supposed apparition site at Medjugorje. The best writing I've encountered on spiritual themes. Hugely entertaining. Occasionally infuriating. Impossible to pin down. Honest. Brave. Sullivan has that rare quality in a writer, the quality of the genuine. If only Christian writers could write like this. But that's the thing. When God uses an atheist, sometimes the atheist, after a genuine conversion, will reveal a light in our faith that the rest of us have never seen.
- recommendation from Heelers of "The Heelers Diaries"