[Iscool]

St. Paul calls himself a doulos.

A servant, of God...Not Mary...Not another man...

[Verginius Rufus]

Doulos is a standard Greek word for "slave." St. Paul is calling himself a slave of Jesus Christ. The idea is not new--some Hebrew or other Semitic personal names mark the bearer as a slave of a deity--like Obediah (slave of Yahweh) or Abdullah (slave of Allah).