... learning how to deal with failure is one of the most crucial skills any pastor needs to acquire.
How do you acquire it?
If failing brings you to the realization that your capabilities, intelligence, likeability and everything else you count as yours - isn't enough, then you learn to depend on Jesus. That my friends, is what Peter had to learn. Not to depend on his leadership abilities, and it appears from what we read that Peter was a natural leader, even though he had never been to seminary - (sarcasm noted) But to depend on Jesus.
Just a couple of examples -
Everyone who comes to your church is not going to grow as a follower of Jesus. Some may even be pretending to be what they are not. If your expectations are that everyone who faithfully attends and participates will prove to be mature when the going gets tough, then you are fooling yourself. People will fail to follow when pressure is applied. They will act in ways that reveal the shallowness, or even complete lack, of faith.
So if they have circled your discipleship bases and you are counting them as home free, the sudden realization that your youth group super star has impregnated the homecoming queen, or your deacon has been caught messing around may shatter you.
However, if you see your part of the work of the church as working with God - not in place of Him - then you'll be equipped to handle whatever comes.
I am not advocating a lowering of our desire to see everyone saved, nor am I saying we should stop working with all we have to see God glorified. What I am saying is to remember that we are all sinners.
We will fail.
It is then Who we call on, and Whose strength and wisdom we turn to when that happens that will determine whether failure makes us a more complete follower of Christ, or a disappointed and discouraged disciple.