A Christian testimony is a believer sharing with others how they came to faith in Christ, what they have witnessed firsthand. It is someone’s public declaration and description of his or her spiritual journey describing the process of salvation. Jesus said, “You will be my witnesses...Go and tell what the Lord has done for you" (Mk 5:18,19; Lk 8:39; Act 1:8). Peter expressed it as, "always being prepared to make a defense to anyone who asks you for a reason for the hope that is in you; yet do it with gentleness and respect" (1 Pet 3:15). We don't have to know all the answers but rather truthfully state the facts, as did the blind man who was healed by Jesus, "One thing I do know, I was blind but now I see” (Jn 9:25).
Even without words our whole lifestyle should speak of Christ
(searching or problems encountered), how you turned (what influenced the decision) and the difference since (forgiveness and peace, etc). This powerful evangelistic tool should not use Christian terminology or jargon ; rather explain what happened to you in words and concepts an unsaved person can relate to and should include a verse or two of Scripture (eg. Rom 3:23, 5:8, 6:23; Act 16:31.
Writing out our unique 'becoming a Christian' story and practicing it with, and being reviewed by other Christians is beneficial. Our testimony must not exaggerate or focus on our shameful past, but rather the grace of God that has brought about this transformation; the purpose is to glorify Christ (not us or Satan) by stating boldly yet with humility the change He has made in our lives, along with the prayer it will encourage others to become believers too. After testifying, situations may arise that will challenge us about living up to our claims and certainly others will be looking for the long-term changes of behaviour, to see if what we have said is valid. A life dedicated to Christ with godly actions matching the words coming from our lips, is a powerful testimony. When we as believers share what Jesus has done in our lives and serve God and others in tangible ways, we will increasingly reflect the life-giving power of Christ into a dark and dismal world.
Today, a testimony can also mean sharing something of particular significance that God has done especially in answer to prayer. The Bible states that believers “triumphed over [Satan] by the blood of the Lamb and by the word of their testimony; they did not love their lives so much as to shrink from death” (Rev 12:11). Our lifesyle and verbal declarations of what Christ has done for us are powerful ammunition in overcoming the attacks of Satan.