readers that his vocation is the reason for his captivity (as a prisoner for the Lord). The Greek preposition en also points to the sphere of his captivity: He is a prisoner “in the Lord.” The exhortation begins by calling the readers to live a life worthy of the calling you have received. The concept of calling is an important one in biblical thought. On a number of occasions the prophets remind the people of Israel that they have been “called” by God to fulfill a specific function (see Isa. 41:9;