Although the deacon is tasked primarily not with teaching the people of God but with mercy ministries such as caring for widows and orphans (Acts 6:1–6), there are many occasions in which deacons will offer instruction. Assisting a family who is suffering a severe budget crisis involves the distribution of funds and advice in how to wisely use the family’s finances. In this case, the deacon will undoubtedly rely on the wisdom and principles of Scripture to help the family learn how to manage their money. When the opportunity comes to help non-Christians, the deacon may very well be called upon to explain the Christian faith and the motivation it provides for doing “good to everyone” (Gal. 6:10). These situations and many others that can possibly arise require deacons to be solidly grounded in the truths of the Bible.
That is why Paul tells us in 1 Timothy 3:9 that deacons, like every other church leader, “must hold the mystery of the faith with a clear conscience.” Paul’s use of the term mystery does not mean that there are secret truths of Christianity that only a select few can grasp. Instead, Paul always uses the word mystery to refer to the content of faith newly revealed by Christ Jesus through His apostles (Rom. 16:25–27; Eph. 1:7–10). The “mystery of the faith” includes things such as final atonement through Jesus’ death and resurrection (a truth not wholly unknown under the old covenant but dimly revealed in the shadows and types of the Mosaic law, Lev. 16; Heb. 9:1–10:18). John Calvin writes that Paul titles the sum of Christian doctrine mystery “as indeed God, through the gospel, reveals to men on earth a wisdom which angels in heaven behold with admiration; and, therefore, we need not wonder if it exceed human capacity.”
Deacons must hold the mystery of faith “with a clear conscience” (1 Tim. 3:9). In other words, their consciences should not accuse them of lying when they profess the Christian faith. A deacon’s confession must not be mere lip service but something that he embraces with both mind and heart. The deacon without a clear conscience lacks the integrity needed to do his job well. More importantly, he lacks saving knowledge of the One whom he claims to serve.