Please read - Luke 22:31-62
All of us make tracks through the valley of failure. The question is, How are you going to respond? Plenty of people give up and exchange a vibrant kingdom-serving life for a defeated existence. But failure need not be an end. It's a chance for a new beginning living in Christ's strength.
Peter had a life-altering failure. Jesus warned that Satan had asked permission to "sift" the disciple like wheat (Luke 22:31)--vigorous shaking is required to separate wheat kernels from debris. The Enemy wanted to shake Peter's faith hard in hopes that he'd fall away from Jesus like chaff.
Peter fervently believed the promise he'd made to Jesus: "Even though all may fall away, yet I will not” (Mark14:29). But Satan knows a few things about the power of fear. What's more, he realized that the disciple would be wounded by his own disloyalty. A man with tattered pride can't help but question his usefulness.
When Satan sifts believers, his goal is to damage our faith so much that we're useless to God. He wants us shelved far from the action of the Lord's kingdom. Therefore, he goes for our strengths--the areas where we believe ourselves to be invincible, or at least very well protected. And when the Devil succeeds, we are disappointed and demoralized. But we don't have to stay that way.
If we are willing, God can use failure to do spiritual housecleaning. Peter laid down his pride and instead put on the Holy Spirit's courage. Thereafter, he risked humiliation, persecution, and death to proclaim the gospel. Failure was the catalyst that brought forth greater faith and true servanthood.
Various quotes about the Enemy
"The Devil often transforms himself into an angel to tempt men, some for their instruction, some for their ruin."
--Augustine of Hippo
"The deceit, the lie of the Devil consists of this, that he wishes to make man believe that he can live without God's Word."
"The existence of the Devil is so clearly taught in the Bible that to doubt it is to doubt the Bible itself."
--Archibald G. Brown
"The Devil can counterfeit all the saving operations and graces of the Spirit of God."
"The Enemy will not see you vanish into God's company without an effort to reclaim you."
--C. S. Lewis
"For where God built a church, there the Devil would also build a chapel."
"That there is a Devil is a thing doubted by none but such as are under the influences of the Devil."
"The more God uses us, the more Satan will attempt to harass us."
--Dr. Charles F. Stanley
"The Devil is a better theologian than any of us and is a devil still."
--A. W. Tozer
"The Devil does not tempt unbelievers and sinners who are already his own."
--Thomas à Kempis