Follow-up increases the effectiveness of a previous decision or action made, by building on, continuing and reinforcing it.
A vital aspect of evangelism
Col 4:12; 2 Tim 1:3,4). It will soon become evident if a person ‘making a decision’ was genuinely convicted of their sin by the Holy Spirit and they were genuinely converted or if they just responded emotionally and will soon fall away when spiritual attacks come.
Follow-up is the spiritual work of shepherding, the grounding or stabilizing a new believer in the faith. It involves protecting, training, guiding, and holding them accountable both in everyday matters and with God so their character and lifestyle come into conformity to that of Jesus (Rom 8:29). There is such a contrast between the Kingdom of darkness and God's Kingdom with the Bible stating we become new creations when we turn to Christ (2 Cor 5:17; Col 1:13). It is extremely beneficial for a new believer to have someone who has already walked this path to help them navigate the way ahead. This should mutate into the life-long process of becoming mature in Christ, making other disciples and utilizing their gifts as they are assimilated into the church. Being a Christian disciple involves a growing relationship with God, the development of Christlike character, and fruitful service for God.
Jesus said, “make disciples, by teaching them…” (Mt 28:19,20). Jesus instructed His disciples, and it was a requirement of those in church leadership to be capable of passing on sound doctrine as contained in the Bible (Mt 11:1; 2 Tim 3:16; Tit 1:9). It is not just getting converts and letting them flounder, rather it requires instructing them in the basics of the Christian faith and being a support to them while they become established, and knitted into a church family (Act 11:26).
Paul revisited the converts made on his first missionary trip, then later when he was unable to make another visit Timothy was sent to teach and establish them (Act 15:36; 1 Thes 3:1,2).