So J.I. Packer once noted that in I Corinthians (c. 54 AD), Paul calls himself the least of the apostles. In Ephesians (c. 61 AD) he calls himself the least of the saints. By I Timothy (c. 65 AD), he describes himself as the chief of all sinners.
Packer's conclusion: Holy people glory, not in their holiness, but in Christ's cross; for the holiest saint is never more than a justified sinner and never sees himself in any other way. (Keeping In Step With the Spirit, page 105)
Hat Tip: Church Matters: The 9Marks Blog