Making disciples requires patience. Not only is the process slow but your disciple will have setbacks along the way. Often these failures do not occur until months or even years into the relationship. I find encouragement in the fact that Peter failed even after spending three years with Jesus. Here he had received life giving instruction, he had experienced a selfless love, he had belonged to a dynamic community, he had tasted personal ministry successes, and he was an eyewitness to many miracles. If anyone should have “known better” it was Peter.
A disciple’s failure is not a disruption to disciple making, rather it is a crucial part of the process. The Holy Spirit puts together perfect circumstances with precise timing in order to test the faith of your disciple. As Fenelon wrote over 300 years ago: “God’s way accomplishes His purpose quicker than anything you could think of. God is able to seek out and destroy the roots of self love. You, on your own, could never find those hidden roots…”  A discipler joins the Holy Spirit during these tests to instruct and demonstrate the grace of God in order to strengthen the faith of his disciple.
Rather than disqualifying your disciple, his worst failure serves as a reference point for the grace of God throughout his life. I doubt the sting of his denial of Jesus ever left Peter. The grace of God does not erase the memories of our sin rather it uses memories to channel our thoughts and emotions to the love of God. A disciple’s failure gives him a benchmark of the depth of the mercy God. No matter how deep his failure the love of God goes even deeper.
It was out of his experience of failure and restoration that Peter could write 30 years later:
“…You may have had to suffer grief in all kinds of trials. These have come so that your faith…may be proved genuine…” (1 Peter 1: 6 &7)
 Fenelon, Francois The Seeking Heart (Jacksonville: Christian Books Publishing House, 1992) p. 10.