We are used to the idea that someone should be appointed to a job because they have the capability to do it. And if you want to progress, then you need to show the competence to succeed at the next level. We know that in practice this isn’t always true, but it’s an ideal we want to hold on to. It naturally leads to the expectation that a person’s position in their career is (or at least should be) a result of their own ability and efforts.
So what are we to make of Jesus’ decision that Simon Peter should become the foundation of the church that would come after him (Matt 16:13-20)? We know only too clearly how woefully unprepared Peter was for this responsibility. He had demonstrated none of the characteristics you might expect to take on this position, and was obviously compulsive and unreliable.
You might argue, based on Matthew’s account, that at least he understood who Jesus was. If that was the key question in the interview then he gave the correct answer. But Jesus himself points out that he deserves no credit for that - the answer had simply been given to him by the Father. Peter might as well have walked into an examination with the answers on a sheet provided by someone else. And it’s far from clear that he understood the answer he was giving - that understanding only came very much later.
God doesn’t select people based on their merits or proven capabilities. David had no proven capabilities when he was chosen as king; the prophets were chosen with no regard for their capabilities, and often despite their desire to avoid the job at all costs. The sudden elevation of Eliakim that Isaiah recounts is another example (Isaiah 22:19-23). Jesus’ choosing of Peter fits exactly into the divine model of personnel selection. It makes no sense to us!
Paul spells it out very clearly: “*For who has known the mind of the Lord or who has been his counselor?” *(Romans 11:33-36) The judgments of God are inscrutable - we should not expect to understand them.
The fact that God has his own reasons for choosing people is both frightening and reassuring. It’s frightening in respect of other people because we want to believe they are capable of doing the job they are called to do. The most obvious example might be Peter and his successors. Some, like Peter himself, turned out to be wonderful shepherds and their sanctity is recognized - others not so much.
The reassurance may come in recognizing that despite the apparently inconsistent appointments God has made, his church continues to proclaim the gospel and strives to remain faithful, despite its clear failures at many times.
At a personal level we can also find the reassurance that if we are found wanting in our competence or ability, we know that God still loves us and has saved us - we don’t have to earn that reward. It has been freely given to us. All we can do is to say with Paul: “For from him and through him and for him are all things. To him be glory forever. Amen.”