Evangelist properly refers to a minister of the Gospel, whose main calling is preaching to the lost, to help them become true Christians.
The term can also be used to refer to a writer of Christian Gospel and is applied to the Apostles Matthew, Mark, Luke, and John.
The term is also loosely applied to Christians, who actively witness to others, with the goal of converting them to the Christian faith, commonly called "evangelizing". Within Churches of Christ the term is used to refer to the person proclaiming the weekly sermon (equivalent to pastor in other denominations; Churches of Christ do not use the terms "pastor" or "reverend").