O man of little faith. While our Lord kindly preserves Peter, he does not connive at Peter's fault. Such is the object of the chastisement administered, when Peter is blamed for the weakness of his faith. But a question arises, Does every kind of fear give evidence of a weakness of faith? for Christ's words seem to imply that, where faith reigns, there is no room for doubt. [1] I reply: Christ reproves here that kind of doubt which was directly opposed to faith. A man may sometimes doubt without any fault on his part; and that is, when the word of the Lord does not speak with certainty on the matter. But the case was quite different with Peter, who had received an express command from Christ, and had already experienced his power, and yet leaves that twofold support, and falls into foolish and wicked fear.

Footnotes

1 - "Que Doute et Crainte ne peuvent avoir lieu ou la foy regne;" -- "that Doubt and Fear cannot have place where faith reigns."

Jesus stretched forth his hand - Every moment we stand in need of Christ: while we stand - we are upheld by his power only; and when we are falling, or have fallen, we can be saved only by his mercy. Let us always take care that we do not consider so much the danger to which we are exposed, as the power of Christ by which we are to be upheld; and then our mountain is likely to stand strong.

And immediately Jesus stretched forth his hand,.... The Syriac reads it, "and in that very moment"; for his case requires immediate assistance, and Christ readily gave it; he reached out his hand at once, being just by him,
and caught him; as he was sinking to the bottom, and lifted him up, and set him on his feet upon the water, and enabled him to walk with him to the ship; but not without reproving him for the weakness of his faith,
and said unto him, O thou of little faith: he does not say, O thou unbeliever! or, O thou who hast no faith! for some faith he had, though but small; of this phrase; see Gill on Matthew 6:30.
Wherefore didst thou doubt? waver, fluctuate, or wast divided between faith and fear. He was worthy of reproof, since he had had the order of Christ to come to him upon the water; and an experience of his power in supporting him thus far; and was now so near unto him, that he had no room to doubt, whether it was he or not, nor of his power to preserve him.

And immediately Jesus stretched forth his hand, and caught him, and said to him, O thou of little faith, why didst thou doubt?--(Also see on Mark 6:50.)

Jesus . . . caught him . . . said, O thou of little faith! Peter's act did not exemplify his faith, but his doubts. True faith never attempts wonders merely for the sake of doing them. It is a fact that ought to be noted that the Gospels narrate the failures in miraculous power on the part of the apostles as well as their success. No book of myths would do this. At the same time it is always made plain why they failed.