Every warrior has a mission, an objective. Our scriptural mandate, our commission from Jesus, is to spread the gospel (something C. S. Lewis called, the good infection). To Paul and the apostles, the sharing of the gospel was paramount. Nothing else mattered as much as this. However, as Lewis pointed out, being able to share the faith means being able to explain it to someone who knows nothing about it.
C. S. Lewis wrote, “If, given patience and ordinary skill, you cannot explain a thing to any sensible person whatever (provided he will listen), then you don’t really understand it yourself.”
Lewis was often concerned that the church creates its own language and set of experiences that are, eventually, taken for granted as normal. They are not really explained; they are assumed. Then what we find is that when we try to explain the faith to others, we fall short, mainly because we have never really thought through what we actually believe ourselves, not to the point where we are capable of explaining it.
Take for example, the resurrection. You can tell a person that Jesus raised from the dead, he resurrected. But what does that mean? Did he have the same body? Was it a transformed body? Was he physical? Then how did He pass through walls? How did He disappear? What does this have to do with me? Even if it happened 2000 years ago, why should I care?
We do a song in our church where we say…
I believe in God our Father
I believe in Christ the Son
I believe in the Holy Spirit
Our God is three in one
I believe in the resurrection
That we will rise again
For I believe in the name of Jesus
Can you explain everything in this song to someone who knows nothing about Christianity? Do they make sense to you? Are they part of your daily experience or are they simply what the church teaches and what the Bible says?
To fulfill our mission, we must know our faith and be able to explain it to others.
We must also know the gospel. The church I attend has broken the gospel up into three parts they call the ABCs: Admit that you are a sinner, Believe that Jesus died for your sin, and Chose Jesus as your Lord and Savior. This is simple and great for the end of a sermon. But the people in our oikos, or circle of influence, who do not know Jesus need to know more.
Take sin, for instance. Can you explain sin in a way that makes sense to a non-Christian? How do you explain to a person that they are a sinner in a way that makes sense?
So what are we to do?
1. Understand that when you share the gospel you are sharing YOUR FAITH, your witness. It is what is real to you in Christianity, in your own personal life. You are the evidence that Christianity works, that it is worth the steep price (we are asking people to give up their entire lives). You would not buy diet pills from a fat doctor. Above all, we must have a vibrant Christian life to share with our oikos.
2. Become aware of what you are weak in or do not understand and study this. I recently realized I did not know very much about Heaven, so I bought a couple of books about Heaven and read them. I have also done more Scriptural studies about Heaven. Now I have a far more comprehensive understanding. 2 Timothy 2:15 “Study to show yourself approved, a workman who need not be ashamed.”
3. Think through and practice sharing the gospel. How do you know what to say if you don’t practice? Think of the objections your friends might bring up and how you would answer them.
4. Be honest, not a salesman. We’re not selling Jesus, we’re sharing with others how they can be saved from their sins, become children of God, and live in glory for all eternity. The only other option for them is an eternity in Hell separated from God. Always keep this cost in mind. This is really eternal life or death.
5. Along with being honest, be willing to say that you don’t know everything, that you are a learner on a life-long journey for understanding God (actually, longer than that). Remember, we’re inviting people to join us on a wonderful journey of discovery.
6. Always remember that God wants our friends and family saved far more than we do. No one comes to Christ without God's intervention. Sharing our faith is partnering with God in His quest to bring all to Him. We must pray for those who we are sharing with. We must ask the Spirit to give us the right words and to know when to speak. We must work with God.
Jesus said, “All authority in heaven and on earth has been given to me. 19 Therefore go and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, 20 and teaching them to obey everything I have commanded you. And surely I am with you always, to the very end of the age.” (Matthew 28:18-20).
 From the essay, “Before We Can Communicate,” in God in the Dock, pg. 256-7