Purpose of a Personal Testimony

Scripture commands that we always be ready to give an answer for the hope that is in us (1 Peter 3:15)
It is an effective tool in sharing Christ by making others aware of what Christ means in your life
While many deny, ignore, and even reject the Scriptures, it is very difficult for them to deny what you say happened in your life and this gives them cause to stop and think
It is a tool that can be used when sharing with a single person or a very large group or anything in between
It is a short, non-preachy, verbal summary of Christ's power in you
It's authenticity is not based on the hearer's theological knowledge or belief in the Bible, but on what they hear you say

Ask for Godly guidance when preparing and sharing your testimony
Write your testimony and edit it several times so it is your best effort
Be brief and interesting, the testimony is not about you, but Christ in you
Include one or two Scripture reference that God used to change your heart and be able to quote them from memory if possible
Be aware of cross cultural teaching issues when sharing your testimony in other cultures
Share your testimony with joy and happiness
Avoid using religious words such as saved, convicted, born-again, sin, and glorious, as these are very often confusing and misunderstood by non-Christians and many in media and politics today use these terms to suggest radicalism, something to be avoided
Avoid references to specific people, churches or denominations, especially in a negative or critical connotation (e.g "I used to belong to that church and it was a dead church and then God opened my eyes")
Avoid an argumentative spirit, your testimony is not designed to defeat people, it is not a debate you are trying to win, but a statement of what God is doing in your life
Avoid preaching and high pressure sales tactics

As in any good presentation, organized thoughts always makes things more clear and helps keep the speaker on track. The Christian testimony should follow this basic outline. The number of sub-points shared in any given situation is determined by many factors such as time, place, and occasion. The flexibility of the outline is that it allows for significant embellishment on the one hand, or a simple four point presentation in three to five minutes.

Introduction

In a presentation setting, you would simply introduce yourself, say where you are from and that you are happy to be there and then something like "I appreciate the opportunity to share with you what Jesus means to me"

Your Life Before You Came To Know Christ

The purpose of this section is establish a point in your life with which the hearer can identify in their own lives
Explain how your life was before you came to know Christ
Seek to identify with hearer by speaking of the intense unmet yearnings that characterized your life, lack of peace, lack of purpose, lack of significance, lack of friends, life without any real meaning, fear of death, etc.
While avoiding the glorification of sin, identify failed strategies you attempted in order to fill the void in your life (work, hobbies, drugs, marriage, sex, sports, poor friendship, etc.)
In the case of some testimonies many of the above "failures" may not have been present so the testimony might say "Over the years of my life, I have noticed many failed strategies people have used to try to fill a void in their lives. For example..."

How You Came To Know Christ

The purpose of this section is to clearly relate the circumstances God used in your life to bring you to Christ
Discuss the person, circumstance, crisis, event, Scriptures, etc. that made you consider the claims of Christ
Explain how you came to understand God's holiness, your sinfulness, Christ's faithfulness and that through trust in Christ your sins were covered

Your Life Since You Came To Know Christ

The purpose of this section is to bear witness to the ongoing changes that are taking place in your life since you began to walk with Christ
Share the fulfillment and purpose you have found in Christ
Share the joy of knowing you have forgiveness of sin and eternal life

Challenge

Finish your testimony with a challenge to your hearers to measure their own lives with power of Christ
With an individual, offer to share a prayer with them

There are three basic testimony types:

The Covenant Child
These are individuals who have grown up in the faith, (not without sin to be sure - Romans 3:23) but the children of believing parents, who were faithfully nurtured in the Word, in prayer, and in the church. Their lives demonstrate they are covenant keepers and heirs to the promises of God (Genesis 12, Galatians 3).

Timothy is an example of such an individual who had known the Holy Scriptures since he was an infant which were able to make him wise unto salvation (2 Timothy 3).

These individuals certainly understand their own sinfulness and need of a Savior and that Christ alone is that savior. Their testimony will not contain a radical "before conversion" but will demonstrate a life of growth in grace, sometimes slower and sometimes faster depending on the circumstances in their lives. It is appropriate to include a statement about what you have seen others try to make their lives meaningful that failed and it is by God's love that you did not follow a similar path but it is in other ways that rebelled against God.

(Note: our culture does not seem to value this type testimony as much as it does one that exhibits a life of radical sin and then conversion. Somehow it is suggested that it takes more of God's grace to save someone from a life of radical sin than sustaining a lifelong faithful walk with Him.) The only ingredient that makes either work is God's grace.

The Conscious Convert
This conversion usually takes place anywhere from the late teens through adulthood. This person has typically pursued many avenues in search of happiness and attempting to fill the void in their life only to be disappointed time and again. Nothing has worked. Some are on this search for a few years, other's for decades.

This individual may have been raised in the church and learned all the right words to say and things to do, but never came to know Christ personally or they may have grown up in a totally pagan world.

At some point, the call of the Spirit of God is heard in their lives and they turn in repentance to Christ for the forgiveness of their sins and life eternal. While the daily struggle in life does not go away, it is no longer empty and they is a sense of purpose and growth where there was once only emptiness. Living for Christ becomes a consuming passion and as a result of that, every area of life is touched.

The Apostle Paul is a clear example of this type conversion and testimony. Acts 9:3f

The Wandering Believer
This individual has a history of walking in the faith, but allowing the Devil a foothold (Ephesians 4:27) in their lives and for a season walks in the shadow of darkness. Typically this individual was raised in the faith and strayed in the teenage years, or even after an adult conversion, they became ensnared by the things of this world and allowed their Christian walk to falter .

In God's own time He called these individuals back to faithfulness. Some in this group will suggest they really were not believers in the first place and confuse God's calling them back to Himself as their real conversion.

David, a man after God's own heart (Acts 13:22) is an example of this type individual and Psalm 51 is a wonderful prayer of confession and repentance, while seeking God's forgiveness and renewal.

Paul's Testimony

It is helpful to read through Paul's own testimony to understand what he said and why he said it. His conversion is recorded in Acts 9:3ff and again in Acts 22 and Acts 26.