How should evangelism be defined? I believe this is to be answered by first answering another question: What is the message that we are to communicate in evangelism? Obviously, the message we are to communicate is the gospel. But what is the gospel? What are some key truths of the gospel that we should seek to communicate to the lost? Once we answer this question, then we’ll be in a proper position to define evangelism. So, let us take a look at some key passages on the gospel in the context of evangelism:
Acts 5:42 “And every day, in the temple and from house to house, they kept right on teaching and preaching [lit. preaching the good news of] Jesus as the Christ.”
Acts 8:12 “But when they believed Philip preaching the good news about the kingdom of God and the name of Jesus Christ, they were being baptized, men and women alike.”
Acts 10:36, 39, 42-43 “The word which He sent to the sons of Israel, preaching [lit. preaching good news of] peace through Jesus Christ (He is Lord of all)…. We are witnesses of all the things He did both in the land of the Jews and in Jerusalem. They also put Him to death by hanging Him on a cross. God raised Him up on the third day and granted that He become visible…. And He ordered us to preach to the people, and solemnly to testify that this is the One who has been appointed by God as Judge of the living and the dead. Of Him all the prophets bear witness that through His name everyone who believes in Him receives forgiveness of sins.”
Romans 10:14-17 “How then will they call on Him in whom they have not believed? How will they believe in Him whom they have not heard? And how will they hear without a preacher? How will they preach unless they are sent? Just as it is written, ‘HOW BEAUTIFUL ARE THE FEET OF THOSE WHO BRING GOOD NEWS OF GOOD THINGS!” However, they did not all heed the good news; for Isaiah says, ‘LORD, WHO HAS BELIEVED OUR REPORT?’ So faith comes from hearing, and hearing by the word of Christ.”
According to our texts we can discern quite a few things regarding the gospel. The following is just a sampling. First of all, the gospel, or good news, is fundamentally about the person and work of Jesus Christ. Every one of our texts displays Jesus as the center of the gospel message. Especially noted in Acts 10 is the crucifixion and resurrection of Jesus Christ, as well as Him being both Judge and Savior. Second, what Jesus accomplished was foretold by the prophets (the Old Testament). In other words, the gospel is historical and according to God’s plan. Third, the gospel is something that is to be proclaimed (a message; news), as well as believed. In fact, people can’t believe in the gospel if the gospel isn’t brought to them. They must first hear the message before they can believe the message. Lastly, the promise of the forgiveness of sins is held out for all those who believe in Jesus Christ (He is Lord, and He has accomplished salvation).
What we have seen is not only the gospel—Jesus Christ crucified and resurrected for the forgiveness of the sins of all those who believe in Him; but it is also evangelism—making known this good news. I think this allows us to formulate a clear and summarized definition of evangelism.
Definition of Evangelism: Evangelism is the discipline of proclaiming or making known, particularly to unbelievers/non-Christians, the historical good news of Jesus Christ having been crucified and resurrected (and the theological significance of these events), of Him being both Judge and Savior, and of Him holding out the promise of the forgiveness of sins to everyone who repents and believes.
Of course, if we wanted to, we could summarize evangelism even further: evangelism is making known the gospel of Jesus Christ to those who have not yet been saved, with the hope that they may be saved. This, of course, does not mean that Christians do not need to have the gospel preached to them. However, evangelism is a technical term that, as we have seen from our sample texts, focuses on or pertains to unbelievers.
 Both “Judge” and “Savior” relate to Jesus as the Christ/Messiah (the “anointed One” of God).
 I know that repentance is not found in any of our sample texts; however, repentance and faith are two sides of the same coin, and therefore one implies the other (e.g. Mk. 1:15; Acts 20:21).