From qualities that have something to do with personal character, Paul turns to a quality that is related to one’s attitude toward the Christian faith: they must hold the mystery of the faith with a clear conscience. The verb hold comes from the verb “to have” but with the extended meaning of being faithful to, adhering faithfully to (so Contemporary English Version “hold firmly”). The term mystery includes the idea of something previously hidden but which is now made known (compare Good News Translation “the revealed truth”). This revealed mystery is the faith, used here to refer either to a body of doctrine that is accepted as true and definitive, or, less likely, to the Christian faith as a religious movement. It is this mystery that they must hold firmly both in their private lives and in their public ministry. And they must do so with a clear conscience. For conscience see discussion in 1.5. There conscience is described as good, whereas here the adjective used is clear. A good conscience enables a person to make good judgment. A clear conscience, on the other hand, is possessed by people who have the conviction that they have done nothing wrong, and whose actions are not motivated by selfish desires. In many languages translators will need to reverse the order of the two clauses in this verse; for example, “They must have a heart that is clear of wrong motives as they continue to believe strongly in the truth of the teachings (or, doctrines) that God has revealed” or “as they continue to believe that the teachings that God has revealed are true.”

Quoted with permission from Arichea, Daniel C. and Hatton, Howard A. A Handbook on Paul’s First Letter to Timothy. (UBS Handbook Series). New York: UBS, 1995. For this and other handbooks for translators see here .