Over and over in the Scriptures, we see examples of God choosing the most unlikely people for an important purpose. And the apostle Paul is certainly a good example. In fact, as one who arrogantly and violently persecuted Christians, he is the last person anyone would ever expect to be transformed into such a humble and faithful advocate for Christ, and used in such powerful ways. But as he wrote to Timothy,

"[Jesus] went out on a limb, you know, in trusting me with this ministry. The only credentials I brought to it were invective and witch hunts and arrogance. But I was treated mercifully because I didn’t know what I was doing—didn’t know Who I was doing it against! Grace mixed with faith and love poured over me and into me. And all because of Jesus.

15-19 Here’s a word you can take to heart and depend on: Jesus Christ came into the world to save sinners. I’m proof—Public Sinner Number One—of someone who could never have made it apart from sheer mercy." (from Eugene Peterson's "The Message," 1 Timothy 1:12-19)