Perhaps the most important question in the world is: “Who do you say Jesus is?” The answer to this determines whether you will find yourself at His right hand or the left, saved or condemned, and filled with joy or weeping for eternity.
He said to them, “But who do you say that I am?” Simon Peter replied, “You are the Christ, the Son of the living God.” And Jesus answered him, “Blessed are you, Simon Bar-Jonah! For flesh and blood has not revealed this to you, but my Father who is in heaven. Matthew 16:15-17 English Standard Version (ESV)
John Calvin says about this question:
But who do you say that I am? Here Christ distinguishes his disciples from the rest of the crowd, to make it more fully evident that, whatever differences may exist among others, we at least ought not to be led aside from the unity of faith. They who shall honestly submit to Christ and shall not attempt to mix with the Gospel any inventions of their own [mind], will never [lack] the true light.
But here the greatest vigilance is necessary, that, though the whole world may be carried away by its own inventions, believers may continually adhere to Christ. As Satan could not rob the Jews of the conviction which they derived from the Law and the Prophets, that Christ would come, he changed [their hoped-for Messiah] into various shapes, and, as it were, cut him in pieces. His next scheme was, to bring forward many pretended Christs, that they might lose sight of the true Redeemer.
By similar contrivances, [Satan] continued ever afterwards either to tear Christ in pieces, or to exhibit him under a false character. Among the confused and discordant voices of the world, let this voice of Christ perpetually sound in our ears, which calls us away from unsettled and wavering men, that we may not follow the multitude, and that our faith may not be tossed about among the billows of contending opinions.
Then, Calvin explains the importance of Peter’s answer:
You are the Christ. The confession is short, but it embraces all that is contained in our salvation; for the designation Christ, or Anointed, includes both an everlasting Kingdom and an everlasting Priesthood, to reconcile us to God, and, by expiating our sins through his sacrifice, to obtain for us a perfect righteousness, and, having received us under his protection, to uphold and supply and enrich us with every description of blessings.
Mark says only, “You are the Christ.” Luke says, “You are the Christ of God.” But the meaning is the same; for the Christs (χριστοί) of God was the appellation anciently bestowed on kings, who had been anointed by the divine command.
And this phrase had been previously employed by Luke, (2:26,) when he said that Simeon had been informed by a revelation from heaven[, which was clearly divine,] that he would not see death before he had seen the Lord’s Christ for the redemption, which God manifested by the hand of his Son; and therefore it was necessary that he who was to be the Redeemer should come from heaven, bearing the impress of the anointing of God.
Matthew expresses it still more clearly, “You are the Son of the living God;” for, though Peter did not yet understand distinctly in what way Christ was the begotten of God, he was so fully persuaded of the dignity of Christ, that he believed him to come from God, not like other men, but by the inhabitation of the true and living Godhead in his flesh. When the attribute living is ascribed to God, it is for the purpose of distinguishing between Him and dead idols, who are nothing, (1 Corinthians 8:4.)
He goes on to describe Christ’s blessing of Peter:
Blessed are you, Simon Bar-Jona. [Peter was blessed in this sense]:
This is life eternal, to know the only true God, and him whom he has sent, Jesus Christ, John 17:3 ESV,
Christ justly pronounces [Peter] to be blessed who has honestly made such a confession. This was not spoken in a [unique] manner to Peter alone, but our Lord’s purpose was, to show in what the only happiness of the whole world consists.
That everyone may approach him with greater courage, we must first learn that all are by nature miserable and accursed, till they find a remedy in Christ. Next, we must add, that whoever has obtained Christ [lacks] nothing that is necessary to perfect happiness, since we have no right to desire anything better than the eternal glory of God, of which Christ puts us in possession.
Finally, Calvin recounts the mechanics of faith:
Flesh and blood has not revealed it to you. In the person of one man [(i.e., Peter)], Christ reminds all [of us] that we must ask faith from the Father and acknowledge it to the praise of his [unmerited favor]; for the special illumination of God is here contrasted with flesh and blood.
Hence, we infer, that the minds of men are destitute of that [discernment] which is necessary for perceiving the mysteries of heavenly wisdom which are hidden in Christ; and [beyond] that, all the senses of men are deficient in this respect, [until] God opens our eyes to perceive his glory in Christ.
Let no man, therefore, in proud reliance on his own abilities, attempt to reach it, but let us humbly suffer ourselves to be inwardly taught by the Father of Lights, (James 1:17,) [so] that his Spirit alone may enlighten our darkness. And let those who have received faith, acknowledging the blindness which was natural to them, learn to render to God the glory that is due to Him.
So, ask yourself, “Who do you say Christ is?”