Because of the decline in Christendom in the modern world, some people outside the faith deem overt expressions of Christianity inappropriate or unacceptable. This makes sharing our faith in a secular workplace or other secular settings challenging. Dr. James Thobaben gives us ancient guidance for modeling and sharing the gospel.
Secularity is growing, not in the sense that fewer and fewer people seek spiritual answers for their lives, but insofar as religious institutions are being pushed to societal margins in the late modern West. Or, to put it more succinctly, globally Christianity is growing even while Christendom is shrinking.
In one sense, that is good. There is little possibility any longer that one can claim to be “bribed” into church attendance with promises of social or economic benefit. No one has to turn to the church for artistic patronage or to justify diplomatic decisions. Seemingly, if the moniker “Christian” is claimed, it is not for earthly advantage but because one truly wants to be such.
On the other hand, the decline of Christendom also means that overt expressions of Christianity will be deemed by some outside the faith as inappropriate for a given venue or even unacceptable in any public setting. This means, quite simply, that offering the gospel, even in the so-called western world, will not be as easily done as in the past.
Guidance can be found in the even more distant past, the times before Constantine and the rise of Christendom in the early 4th century. For instance, “The Epistle of Mathetes to Diognetus,” perhaps written as early as AD 130, provides a description of how to be Christian in a secular setting.
For the Christians are distinguished from other [persons] neither by country, nor language, nor the customs which they observe. … They dwell in their own countries, but simply as sojourners. As citizens, they share in all things with others, and yet endure all things as if foreigners. Every foreign land is to them as their native country, and every land of their birth as a land of strangers. … They are in the flesh, but they do not live after the flesh. They pass their days on earth, but they are citizens of heaven. They obey the prescribed laws, and at the same time surpass the laws by their lives. … they are dishonoured, and yet in their very dishonour are glorified. They are evil spoken of, and yet are justified; they are reviled, and bless… 
Realizing, as did Mathetes, the need to wisely consider circumstances, here are ten prudential rules. Other may approach testifying in different ways, but these seem effective in serving the end of “proclaiming the good news” to “ears that can hear” (Matthew 11:15):
- Begin each day in assurance. The starting point of evangelism is accepting anew the good news for oneself. If one has a proper relationship with God, then proper relationships with others are far more likely. Assurance yields confidence, and confidence becomes courage (Romans 8:38-39). Courage is the willingness to act prudentially without rashness or cowardice. The one who lives according to Christ is empowered by His Spirit and need not fear a secularized world.
- Do good quality work. One should distinguish when and when not to speak of spiritual things. Most often in a secular employment setting, focus on the so-called job at hand, and the Spirit will provide opportunities to witness. Further, that focus should lead to excellence at the secular task. God is not the God of mediocrity. As Paul said, “Whatever you do, work at it with all your heart, as working for the Lord…” (Colossians 3:23-24 NIV).
- Even beyond specific employment tasks, look for ways to cooperate on joint activities that are considered by others supererogatory. This word means “morally superior actions” or “good works beyond that which is required.” Of course, in our tradition, such is not extra; we are to do any and all to which we are called (Luke 17:10). Shared efforts with non-believers based on “middle axioms,” that is, proximate value agreements, provide a means to establish mutual respect (II Corinthians 5).
- Extending this, intentionally help individuals in need, not just believers but also those outside the church, even when not legally or contractually obliged to do so. In a work or volunteer organization, work to gain a reputation for being helpful and polite. Go beyond the required to help the forgotten, the broken, the mistreated. Works of mercy virtually guarantee an opportunity to witness that cannot be readily dismissed. As our Lord said, “Your light must shine before people in such a way that they may see your good works, and glorify your Father who is in heaven” (Matthew 5:16 NASV).
- Learn to give in to others, perhaps especially non-Christians, on that which does not eternally matter. If the gospel offends, then so be it – but believers should not be offensive in how they interact. While it is true that “sweetness” is not among the fruits of the Spirit, gentleness and kindness are (Galatians 5:22-23). To use the somewhat harsh words of our Lord, “Do not cast pearls before swine” (Matthew 7:6). Even so, as Paul said of our living out the gospel, “Insofar as possible, be at peace with all” (Romans 12:18).
- Develop the habit of patience in adversity. Learn to expect mockery. Christians have legal rights like anyone else and can appeal to such, just as Paul did with his Roman citizenship (Acts 25:11). Yet, short of such, they must simply persevere, knowing it leads to fulfilled hope (Romans 5:3-5).
- Find other Christians to encourage and hold you accountable. As John Wesley famously said, “The gospel of Christ knows of no religion but social; no holiness but social holiness.” The author of Hebrews said, “And let us consider how we may spur one another on toward love and good deeds… encouraging one another—and all the more as you see the Day approaching” (Hebrews 10:24-25).
- Maintain personal purity by avoiding gossip, maintaining relational and sexual boundaries, etc. We each need to do this simply to maintain our spiritual readiness for the gospel. Such temperance also provides protection from accusations of hypocrisy. Many in the world will look for cracks in the characters of Christians as an excuse to not take the gospel seriously. As Peter said, “Live such good lives among the pagans that, though they accuse you of doing wrong, they may see your good deeds and glorify God on the day he visits us” (I Peter 2:1, 11-12 NIV).
- Now, at last, testify. Being deferential, appropriately ‘keeping one’s head down,’ working with non-Christians, and having good manners do not mean one should not speak the Truth as warranted. People will ask, so be ready to speak. Help them understand they can be part of the narrative of Christ, that they can have meaning and eternal value in Him. What Paul said to Timothy applies to us all in one sense or another: “Preach the word; be prepared in season and out of season…” (2 Timothy 4:5 NIV).
- Commit yourself to never be ashamed of the gospel. End each day being able to look back to how you began, with assurance. Christ warned, “Behold, I am sending you out as sheep in the midst of wolves; so be as wary as serpents, and as innocent as doves” (Matthew 10:16 NASV) but did so to give us courage and confidence in Him (Romans 1:16-17; I Corinthians 15:3-11).
Our days are no worse than those before and better than many. The very minor problems that Christians face in the U.S. pale in comparison with those that believers around the world must confront. The end of Christendom is not the end of the faith. So, as you have an opportunity, share the story that is hope, even in an antagonistic world.
 Chapt. 5, Matthetes. 1885. “The Epistle of Mathetes to Diognetus.” In Ante-Nicene Fathers, translated by Alexander Roberts, James Donaldson, and A. Cleveland Coxe. Vol. 1. Christian Literature Publishing Co. (Buffalo, N.Y.).