“Let your light so shine before others so that, seeing your good actions, they will praise your Father who is in heaven.” Matthew 5:16 (paraphrase)
I am studying the Sermon on the Mount found in Matthew 5-7. In my studying, I came across a commentary by Scott McKnight. In it, he says, “…reading or teaching or preaching the Sermon on the Mount is evangelism.”
This struck me as an interesting topic, one that keeps coming up in my studies on evangelism.
When we think of evangelism we usually think about preaching the cross, how Christ died to save us from our sins, and those that believe in him will not see the judgment of God but will receive eternal life. This is a very different message than the Sermon on the Mount. What we see in this sermon of Jesus are commands and exhortations about how to live life. But, could living the life we find in Jesus sermon help us to shine our light on the world and draw people to Jesus Christ?
Scott McKnight illustrates a story about a Hindu student of his that warmed up to Christianity in his class. He said, “This Hindu student of mine was attracted to Jesus because of the Story of Jesus she read in the Gospels.”
Dr. Martyn Lloyd-Jones makes the same idea. He says, “I suggest to you [the Sermon on the Mount] is the best means of evangelism…The world today is looking for, and desperately needs, true Christians…If only all of us were living the Sermon on the Mount, men would know that there is a dynamic in the Christian gospel…” 
What these two authors, published in different two centuries are saying, is, if the Church of Jesus Christ started to act like it followed Jesus Christ, the world would see and believe, and they two will follow Christ.
 Scott McKnight, The Story of God Bible Commentary: Sermon on the Mount, (Zondervan, 2013) Kindle Location: 841
 D. Martyn Lloyd-Jones, Studies in the Sermon on the Mount, (Inter-Varsity Press, 1960) pg. 18-20