Our Lord calls all of us to witness to Him and the gospel of salvation from sin and death by Him; and calls not only those who hold the office of minister, but all who hold the office of Christian; and to do that not only passively but actively; not only by mouth but by deed; and not only some days but every day of our life. This calling is not optional, something to choose to do or not do, accept or reject. If we are a Christian in whom the Spirit of Jesus dwells by faith, we must and will witness to our Christ and His salvation.
Our Lord calls some to witness officially in special offices, especially prophet, apostle, and minister. The righteousness of God by faith without works was witnessed by the prophets because they witnessed of Christ (Rom. 3:21; Acts 10:43). The apostles were called to witness of Jesus as those with Him from the beginning (John 15:27). And with great power they witnessed of all things He said and did, and were special eye-witnesses of His resurrection and eternal life (Acts 1:22; 2:32; 3:15; 4:33; 10:39; 1 John 1:2). Paul was called to witness what he personally saw and heard from Jesus, of things small and great, which was nothing other than what Moses and the prophets had said (Acts 22:15; 26:22). Timothy witnessed a good confession before others even as Jesus witnessed a good confession before Pilate (1 Tim. 6:12–13). And by such ministers, the gospel of the kingdom continues to be preached for a witness unto all nations (Matt. 24:14).
But every individual in the church is also called to witness to Jesus and the gospel in the office of Christian. The saints listed in Hebrews 11, many who did not hold a special office, are all called a great cloud of witnesses (Heb. 12:1). The saints in heaven are called those who died for their witness of Jesus Christ and the Word (Rev. 20:4). Before He ascended, Jesus said all who received His Spirit would be witnesses of Him unto the uttermost parts of the earth (Acts. 1:8). And He says that we are the light of the world, that is, witnesses to the world (Matt. 5:14).
The explanation, first, is that Jesus Christ is the faithful and true Witness and the Light of the world (John 9:5). For this cause was He born and came into the world, that He should bear witness of the truth (John 18:37). He is witness of God the Father and the Spirit as the beginning of the creation and first begotten from the dead; and by words and deeds given Him to do, God the Father and God the Spirit are the two great, infallible and faithful witnesses of Him as God the Son (John 5:36–37; 10:25; Rev. 1:15; 3:14). And so also are we, His members.
The explanation, secondly, is that by the will of God the Father, the living Spirit of the resurrected Son lives in us by faith and we share in His office as Christians. As such, we witness not only passively as lights on a candlestick, but actively as persons both before the church and the world; and not only some days, but every day of our new life by word and deed. We are prophets called to confess His name; priests called to present our lives as living sacrifices of thanksgiving; and kings given power to fight against sin and Satan. One reason we must still do good works is that, saved by grace without works, by our godly life others may be gained to Christ by the witness of the whole of our conversation (Heidelberg Catechism, LD 32). Like the witness of the apostles, this new life powerfully witnesses to everything Jesus said and did, especially His resurrection life graciously given us by the will of the Father and power of His Spirit.
Paul referenced such personal witness when he said of the entire church at Thessalonica, For from you sounded out the word of the Lord…in every place your faith to God ward is spread abroad; so that we need not to speak anything (1 Thess. 1:8). The idea is that wherever each church member went into the world for work or play, their faith also went and witnessed by word and deed so that God’s Word was spread abroad.
In this coming year, let us remember we are witnesses; and that if we receive the witness of men, the witness of God is greater; and that whosoever believes in the Son has this witness of God in himself and witnesses powerfully by word and deed that God has given to us eternal life and this life is in His Son (1 John 5:9–11).