The growth of the Church stems from the strength and depth of the testimonies gained and developed by the membership prior to and following baptism. That is a given. However, frankly, I think the Church blossoms in direct proportion to how well regular members and local leaders understand the concept of friendship and fellowship - since I think that is the essence of what Jesus taught and lived. Yes, He taught ideals that often were even stricter than the original 10 Commandments, but He also put His arms around anyone who would open up to them - living among saints and sinners alike and, particularly, embracing those whom no others would embrace.
I wonder sometimes, "Who are the lepers in our modern society - or even in the Church? Who is the women taken in adultery? Who are the untouchables Jesus would have touched - the unembraceable ones Jesus would have embraced?" I then wonder, "Am I touching and embracing them in any significant way?"