"I am more convinced that it is only when you and I and others who are members of the Christian Church, are rejoicing in this abounding grace as we ought to be, that we shall begin to attract the people who are outside the Church. That is my understanding of evangelism. If you and I and all other Christians walked through this world as men and women who are experiencing the 'abundance of grace' and this 'much more', we should find that people would stop us at work, and in the business and or the profession and they would say, "Tell me, what is this? I want to know about it I want it for myself." " Martyn Lloyd-Jones on Romans 5.15 (taken from Romans - Exposition of Chapter 5, Assurance, published by Banner of Truth, pp.238-39)
It's not the whole story on evangelism, but the "Doctor", as he was affectionately known, was on to something here.