Christianity is all about making disciples. Introducing the unsaved and the saved alike, to Jesus. For it is the same Gospel of Jesus' death, burial, resurrection, and enthronement that gets sinners saved and teaches Christians how to live saved. Consider the following Scripture:
 For when the time was right, the Anointed One (Jesus) came and died to demonstrate His love for sinners who were entirely helpless, weak, and powerless to save themselves.
Now, would anyone dare to die for the sake of a wicked person? We can all understand if someone was willing to die for a truly noble person. But Christ proved God’s passionate love for us by dying in our place while we were still lost and ungodly!
And there is still much more to say of his unfailing love for us! For through the blood of Jesus we have heard the powerful declaration, “You are now righteous in my sight.” And because of the sacrifice of Jesus, you will never experience the wrath of God. So if while we were still enemies, God fully reconciled us to Himself through the death of His Son, then something greater than friendship is ours. Now that we are at peace with God, and because we share in His resurrection Life, how much more we will be rescued from sin’s dominion!
And even more than that, we overflow with triumphant joy in our new relationship of living reconciled to God—all because of Jesus Christ!                                                                         (Romans 5:6-11, the Passions, emphasis mine)
For the unsaved Pastor Paul describes the Gospel like this: 
Now I would remind you, brothers, of the Gospel I preached to you, which you received, in which you stand, and by which you are being saved, if you hold fast to the word I preached to you—unless you believed in vain... For I delivered to you as of first importance what I also received: that Christ died for our sins in accordance with the Scriptures, that He was buried, that He was raised on the third day in accordance with the Scriptures, and that He appeared to Cephas, then to the twelve. Then He appeared to more than five hundred brothers at one time, most of whom are still alive, though some have fallen asleep. Then He appeared to James, then to all the apostles. Last of all, as to one untimely born, he appeared also to me. For I am the least of the apostles, unworthy to be called an apostle, because I persecuted the church of God. But by the grace of God I am what I am, and His grace toward me was not in vain. On the contrary, I worked harder than any of them, though it was not I, but the grace of God that is with me. Whether then it was I or they, so we preach and so you believed.                                 
(1 Corinthians 15:1-11, emphasis mine)
And describing Jesus as the Gospel, Pastor Paul used these words: 
I, Paul, am a devoted slave of Jesus Christ on assignment, authorized as an apostle to proclaim God’s words and acts. I write this letter to all the believers... God’s friends.
The sacred writings contain preliminary reports by the prophets on God’s Son. His descent from David roots Him in history; His unique identity as Son of God was shown by the Spirit when Jesus was raised from the dead, setting Him apart as the Messiah, our Master. Through Him we received both the generous gift of His Life and the urgent task of passing it on to others who receive it by entering into obedient trust in Jesus. You are who you are through this gift and call of Jesus Christ!                                                                                                                 
(Romans 1:1-7, the Message, emphasis mine)
And finally, the Pastor invites everyone to be saved through this one and only path (truth): 
If you confess with your mouth that Jesus is Lord and believe in your heart that God raised Him from the dead, YOU WILL BE SAVED. For with the heart one believes and is justified, and with the mouth one confesses and is saved.                                                                                (Romans 10:9-10, emphasis mine)
Then Pastor Paul addresses the saved with this same Gospel.  
I have been crucified with Christ. It is no longer I who live, but Christ who lives in me. And the Life I now live in the flesh I live by faith in the Son of God, who loved me and gave Himself for me.  (Galatians 2:20, emphasis mine)
Eugene Peterson captured the Pastor words in with this down-to-earth strategy. 
What actually took place is this: I tried keeping rules and working my head off to please God, and it didn’t work. So I quit being a “law man” so that I could be God’s man. Christ’s Life showed me how, and enabled me to do it. I identified myself completely with Him. Indeed, I have been crucified with Christ. My ego is no longer central. It is no longer important that I appear righteous before you or have your good opinion, and I am no longer driven to impress God. Christ lives in me. The Life you see me living is not “mine,” but it is lived by faith in the Son of God, who loved me and gave Himself for me. I am not going to go back on that. 
Is it not clear to you that to go back to that old rule-keeping, peer-pleasing religion would be an abandonment of everything personal and free in my relationship with God? I refuse to do that, to repudiate God’s grace. If a living relationship with God could come by rule-keeping, then Christ died unnecessarily.
(Galatians 2:19-21, the Message, emphasis mine)
And Brian Simmons expresses this Bible verse with much practicality. 
My old identity has been co-crucified with Christ and no longer lives. And now the essence of this new Life is no longer mine, for the Anointed One lives His Life through me—we live in union as one! My new Life is empowered by the faith of the Son of God who loves me so much that He gave Himself for me, dispensing His life into mine!                                                            (Galatians 2:20, the Passion, emphasis mine)
Finally, we see Jesus commissioning us to make disciples. And there's one thing we must remember about true disciples. Disciples make disciples
Jesus came and said to them, “All authority in heaven and on earth has been given to me. Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all that I have commanded you. And behold, I am with you always, to the end of the age".                                                               
(Matthew 28:18-20, emphasis mine)
Again, from Eugene Peterson: 
Jesus, undeterred, went right ahead and gave his charge: “God authorized and commanded me to commission you: Go out and train everyone you meet, far and near, in this way of Life, marking them by baptism in the threefold name: Father, Son, and Holy Spirit. Then instruct them in the practice of all I have commanded you. I’ll be with you as you do this, day after day after day, right up to the end of the age.                                                                                 
(Matthew 28:18-20, the Message, emphasis mine)