I spent years of my christian life believing that some people are unfit to serve God. Recently I was called into account for that past belief and looking back at it I have to admit I was wrong (pick my wife up off the floor). Although I can think of positions of service that perhapse should be guarded I can think of nothing finer than an "experienced sinner" getting the opportunity to minister to other sinners.
What is this oportunity that God has given us to share his word with the entire world. Love that is so strong to pull us from our sinful way and lead us to God's arms. Who are we to say who should and should not serve, who are we to say who should and should not worship.
One verse that I have been going over in the process of "working out" my salvation (Phl 2:12-13) uses the word "ALL."
2Pe 3:9 The Lord is not slack concerning his promise, as some men count slackness; but is longsuffering to us-ward, not willing that any should perish, but that all should come to repentance.
The word "all" is all without exception. All that God has given to Jesus for salvation will be saved. It doesn't matter what we think about the person that God chooses for salvation, even the unlikely disciples that are among them. There is a song by Casting Crowns that has an interesting tag line to the last chorus.
Jesus paid much too high a price
For us to pick and choose who should come
And we are the Body of Christ.
If We Are The Body by Casting Crowns
What a start to the day.