Evangelism is the work of a Christian evangelist, of which all true Christians are obligated to partake to some extent, which seeks to persuade other people to become Christian, especially by sharing the basics of the Gospel, but also the deeper message of biblical truths. Today the Gospel is almost an unknown, so what does the Christian evangelist do? Preevangelism is laying a foundation for those who have no knowledge of the Gospel, giving them background information, so that they can grasp what they are hearing. The Christian evangelist is preparing their mind and heart so that they will be receptive to the biblical truths. In many ways, this is known as apologetics.
Christian apologetics [Greek: apologia, "verbal defense, speech in defense"] is a field of Christian theology which endeavors to offer a reasonable and sensible basis for the Christian faith, defending the faith against objections. It is reasoning from the Scriptures, explaining and proving, as one instructs in sound doctrine, many times having to overturn false reasoning before he can plant the seeds of truth. It can also be earnestly contending for the faith and saving one from losing their faith, as they have begun to doubt. Moreover, it can involve rebuking those who contradict the truth. It is being prepared to make a defense to anyone who asks the Christian evangelist for a reason for the hope that is in him or her. – Jude 1.3, 21-23; 1 Pet 3.15; Acts 17:2-3; Titus 1:9.
What do we mean by obligated and what we mean by evangelism are at the heart of the matter and are indeed related to each other.
EVANGELISM: An evangelist is a proclaimer of the gospel or good news, as well as all biblical truths. There are levels of evangelism, which is pictured in first-century Christianity. All Christians evangelized in the first century, but a select few fit the role of a full-time evangelist (Ephesians 4:8, 11-12), as Philip and Timothy were.