John Calvin Commentary Matthew 14:31

"And immediately Jesus stretched forth his hand, and took hold of him, and saith unto him, O thou of little faith, wherefore didst thou doubt?" — Matthew 14:31 (ASV)

O man of little faith. While our Lord kindly preserves Peter, he does not overlook Peter’s fault. Such is the purpose of the chastisement given, 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.³⁸⁴

I reply: Christ here reproves that kind of doubt which was directly opposed to faith. A person may sometimes doubt without any fault on their part; this occurs when the Word of the Lord does not speak with certainty on the matter. But the case was quite different with Peter. He had received an express command from Christ and had already experienced his power, yet he leaves that twofold support and falls into foolish and wicked fear.

³⁸⁴ “Que Doute et Crainte ne peuvent avoir lieu ou la foy regne;” — “that Doubt and Fear cannot have place where faith reigns.”;” — “that Doubt and Fear cannot have place where faith reigns.”