Evangelism is communicating the gospel of Jesus Christ with the immediate intent of converting the hearer to faith in Christ, and with the ultimate intent of instructing the convert in the Word of God so that he can become a mature believer. 

How then should evangelism be defined? The N.T. answer is very simple. According to the N.T., evangelism is just preaching the gospel, the evangel. Evangelizing, therefore is not simply a matter of teaching, and instructing, and imparting information to the mind. There is more to it than that. Evangelism includes the endeavor to elicit a response to the truth taught. It is communication with a view to conversion. It is a matter, not merely of informing, but also of inviting.