Ephesians 4:10-12 English Standard Version (ESV)
10 He who descended is the one who also ascended far above all the heavens, that he might fill all things.) 11 And he gave the apostles, the prophets, the evangelists, the shepherds and teachers, 12 to equip the saints for the work of ministry, for building up the body of Christ,
Ephesians 4:11 teaches that one particular order of the ministry, distinguished from every other, is singled out by the Head of the church for this work in a distinctive sense. All may possess the gift of an evangelist in a measure, and be obligated to exercise its privilege and duty, but some are specially endued with it. “He gave some to be apostles; and some, prophets; and some, evangelists; and some, pastors and teachers.” It will be seen that as an order in the ministry, the evangelist precedes that of the pastor and teacher, a fact which harmonizes with the character of the work each is still recognized as doing. The evangelist has no fixed place of residence, but moves about in different localities, preaching the gospel to those ignorant of it before. As these are converted and united to Jesus Christ by faith, the work of the pastor and teacher begins, to instruct them further in the things of Christ and build them up in the faith. (Source International Standard Bible Encyclopaedia)
This is a clear indication that discipleship can only be performed on those who are recently born again. The work of the evangelist must happen first and conversion performed. The lost cannot be discipled because of one detail that is often overlooked and should be a part of every discipleship program.
1 Corinthians 8:2 English Standard Version (ESV)
2 If anyone imagines that he knows something, he does not yet know as he ought to know.
Imagination is a function of the natural mind. Truth is a revelation of the Spirit to those abiding in Christ. The lost do not have the Holy Spirit to guide them in all truth.