People do not understand that they cannot make one disciple of Jesus by just sharing the Gospel. Sharing the Gospel is like sowing the seed. Once the seed spouts it has to be guided by a proper church to water the plant often. Many evangelists miss this part and they think they are doing a complete ministry. Jesus said in Acts 1:8 that when you receive Baptism of Holy Spirit you will be my witness. To be witness means our being itself will be a witness for Christ just like how the being of Christ itself on this earth manifested eternal life (1 John 1:2). But many Christians only bear witness which means only their lips talk about Jesus without any life witness.
_________________Sreeram