I recently attended a promotional event for a Christian camp. According to the various speakers, the camp is a successful ministry and is being mightily used by God because such and such a number of campers 'made decisions' to follow Christ. That's a predictable scenario at Christian fundraising events, but we need to ask ourselves if this is a good and biblical measure of ministry success. More to the point, are 'decisions' the goal of Christian evangelism? Tim Keller helpfully answers this question as follows:
"The 'Great Commission' is not just a call to 'make disciples' but to 'baptize'. In Acts and elsewhere, it is clear that baptism means incorporation into a worshipping community with accountability and boundaries (cf. Acts 2:41ff.). Much traditional evangelism aims to get a 'decision' for Christ. Experience, however, shows us that many of these 'decisions' disappear and never result in changed lives. Why? Many, many decisions are not really conversions, but often only the beginning of a journey of seeking God. (Other decisions are very definitely the moment of a 'new birth,' but this differs from person to person.) Only a person who is being evangelized in the context of an on-going worshipping and shepherding community can be sure of finally coming home into vital, saving faith." (source unknown)
Only one on-going, worshipping and shepherding community is presented in the Bible: the local church. Therefore, even if a person comes to faith in Christ outside of the local church, they should be quickly and deeply integrated for their dicipleship and maturation. The Bible simply offers no category for a believer (new or old) who is disconnected from the local church.