What does 1 Timothy 3:9 mean?

In addition to the character qualifications given in verse 8, deacons must be those who hold faithfully to the foundational truths of the gospel. "Mystery of the faith" is a phrase unique to this verse. However, the more general concept of "mystery" is mentioned in verse 16. This is a common theme in Paul's writings. Paul's use of it has more to do with the progressive revelation of God, not some elite secret (Romans 16:25). Paul often spoke of the revelation of Jesus Christ, as the resurrected Messiah, as a revealed mystery. Deacons were to hold to this foundational truth.

The concept of a "clear conscience" is also given great importance in this verse. Paul mentioned the importance of "conscience" or "consciences" several times in this letter (1 Timothy 1:5, 19; 4:2) and often in his other letters. Paul said he had a clear conscience as well (2 Timothy 1:3). It is important for church leaders to be those who follow their conscience, as guided by God. Those who struggle to "do the right thing," violating their conscience, should not be considered for leadership. This seems to be supported by Paul's comments about "testing" in the next verse.