proclaiming the Christian gospel; an activity designed to spread Christianity

spreading the Christian message

The gift of Evangelism is the special ability God gives to certain members of the body of Christ to share the gospel with others in such a way that they come to know God's love & recognize that we are a welcoming community. (see Ephesians 4:11-14, 2 Timothy 4:5, Acts 8:5-6, Acts 8:26-40, Acts 14:21, Acts 21:8)

proclamation of the Gospel or "good news" of Jesus Christ

Greek euangelistes, "bringer of good news" -- preaching or spreading the Gospel; any zealous effort in propagandizing for a cause. Evangel is another word for Gospel. Evangelical is in, of, or according to the Gospels of the New Testament, generally Protestant churches that emphasize salvation by faith in the atonement of Jesus rather than the efficacy of the sacraments and good works alone.

the attempt to convert others by proclaiming and convincing them of the truth and power of religious belief

The act or process of encouraging persons to accept Christ.

Evangelism is the proclaiming of the Christian Gospel or, by extension, any other form of preaching or proselytizing. The word evangelist comes from the Koine Greek word ευαγγελιον (transcribed as "euangelion") via Latin "Evangelium", as used in the canonic titles of the four Gospels, and thus The Evangelists are the authors of the four Gospels -- traditionally known as Matthew, Mark, Luke, and John (also known as the Four Evangelists). The Greek word ευαγγελιον originally meant a reward for good news given to the messenger (ευ = "good", αγγελλω = "I bring a message"; the word angel is of the same root) and later "good news".