This was a critical time in the Lord Jesus Christ’s service to humankind. The ruling leadership was plotting his murder with one of His inner circle of disciples, Judas. Jesus had sent Peter and John ahead to prepare for a significant religious dinner celebration.

Then, at that dinner, while instructing His disciples of His impending death and resurrection, a controversy over who was the greatest disciple broke out. After Jesus taught them the meaning of humility and about their future roles as his disciples, He tells Peter how he will betray Him:

“Simon, Simon, behold, Satan demanded to have you, that he might sift you like wheat, but I have prayed for you that your faith may not fail. And when you have turned again, strengthen your brothers.” Peter said to him, “Lord, I am ready to go with you both to prison and to death.” Jesus said, “I tell you, Peter, the rooster will not crow this day, until you deny three times that you know me.” Luke 22:31–34 English Standard Version (ESV)

Calvin explains:

…When Christ formerly promised to his disciples the spirit of unshaken fortitude, he referred to a new state of things which followed the resurrection; and, therefore, as they were not yet [endowed] with heavenly power, Peter, forming confident expectations from himself, goes beyond the limits of faith.

…This claims our attention, that every man, remembering his own weakness, may earnestly resort to the assistance of the Holy Spirit [through prayer]; and next, that no man may venture to take more upon himself than what the Lord promises. [Thus,] Paul…enjoins us to:

…Work out our salvation with fear and trembling, because it is God that works in us to will and perform, (Philippians 2:12 – 13.)

…Therefore, whenever any temptation is presented to us, let us first remember our weakness, that, being entirely thrown down, we may learn to seek elsewhere [i.e., from God] what we need [i.e., His mercy and grace]; and, next, let us remember the grace which is promised, that it may free us from doubt.

So, we must rely on Christ and not on our own strength. However, this is not the end of the matter. Christ, through His servant Paul, challenges us:

Examine yourselves, to see whether you are in the faith. Test yourselves. Or do you not realize this about yourselves, that Jesus Christ is in you? — unless indeed you fail to meet the test! 2 Corinthians 13:5 (ESV)

And Calvin says:

…But what does Paul say here? He declares, that all are reprobates, who doubt whether they profess Christ and are a part of His body. Let us, therefore, reckon…right faith [is that] which leads us to [rest] in safety in the favor of God, with no wavering opinion, but with a firm and steadfast assurance.

They admonish us because God supplies saving faith; it is not our own doing:

For by grace you have been saved through faith. And this is not your own doing; it is the gift of God, not a result of works, so that no one may boast. For we are his workmanship, created in Christ Jesus for good works, which God prepared beforehand, that we should walk in them. Ephesians 2:8-10 (ESV)

Yet, facing ourselves more deeply, let us not forget the parable of the soils. As Christ explains:

Now the parable is this: The seed is the word of God. The ones along the path are those who have heard; then the devil comes and takes away the word from their hearts, so that they may not believe and be saved.

And the ones on the rock are those who, when they hear the word, receive it with joy. But these have no root; they believe for a while, and in time of testing fall away.

And as for what fell among the thorns, they are those who hear, but as they go on their way they are choked by the cares and riches and pleasures of life, and their fruit does not mature.

As for that in the good soil, they are those who, hearing the word, hold it fast in an honest and good heart, and bear fruit with patience.

Luke 8:11-15 (ESV)

Let us therefore exercise patience in our calling because He cannot fail; though we may:

My flesh and my heart may fail,

   but God is the strength of my heart and my portion forever.

Psalm 73:26 (ESV)

To this, Calvin reveals:

…There is here a contrast between the failing which David felt in himself and the strength with which he was divinely supplied; as if he had said, “Separated from God I am nothing, and all that I attempt to do ends in nothing; but when I come to him, I find an abundant supply of strength.”

It is highly necessary for us to consider what we are without God; for no man will cast himself wholly upon God, but he…who despairs of the sufficiency of his own powers. We will seek nothing from God but what we are conscious of [lacking] in ourselves.

Then, let us cast ourselves wholly upon Him that our faith may not fail.

The Denial of Saint Peter, circa 1610, by Michelangelo Merisi da Caravaggio (1571 – 1610), public domain in the United States