Answer: 1. The Christian cause
In his letters to the different churches, Apostle Paul stresses that every believer’s chief duty is to promote the Christian cause which seeks to save all that are yet unsaved.
Seeing as Christ’s gift of Salvation is yet to be received by many people, every believer, according to Paul, is tasked with the assignment of witnessing Christ to as many people as possible in order to further God’s Kingdom and Salvation plan on the earth.