Mark 9:23

‘And Jesus said to him, “If you can? All things are possible to him who believes.” '.

The probable text is ‘to 'ei dune' making the ‘if you can' a noun equivalent. Jesus was saying, “you have said ‘if you can'. But to him who believes (what I can do) all things are possible.' The strength of the argument is not that if the man has sufficient faith the boy can be healed, but that if the man has sufficient faith in Jesus Himself then he can be. And it was necessary for him to have faith in Jesus. He must put aside his doubt and place full confidence in Him. For Jesus is concerned that the man should be faced up with his response, not only to God but to Jesus Himself. (The man's reply demonstrates that he saw that it was his own faith that was in question).

Alternately Jesus may be pointing out to the man that he need not have doubts for all things are possible to Him because He, Jesus, truly believes. There is not question of ‘if'. Let him rest on that. Certainly in the remainder of the passage the emphasis is on the faith or lack of faith of the healer. But if so the man either misunderstood Him or else reacted to the words and applied them to himself as well.