I am sure that you have heard different versions of this thought before. Brennan Manning is credited with saying “The single greatest cause of atheism in the world today is Christians, who acknowledge Jesus with their lips, then walk out the door, and deny Him by their lifestyle. That is what an unbelieving world simply finds unbelievable."
The heart of what both these men are saying is that the way we live provides the evidence for the truth of what we say. When we say we follow Jesus and tell others that they should follow Jesus, but there is no difference in the way we live, then why would people want to follow Jesus? To say that Jesus gives us hope and life, but those things are not evident in the way we live we are proclaiming to the world that the promises of Jesus are hollow and empty. It takes more than apologetics and evangelism techniques to make true followers of Jesus. What is needed is a way of life that people can immediately tell is a better way to live.
But even if you should suffer for righteousness' sake, you will be blessed. Have no fear of them, nor be troubled, but in your hearts regard Christ the Lord as holy, always being prepared to make a defense to anyone who asks you for a reason for the hope that is in you; yet do it with gentleness and respect, having a good conscience, so that, when you are slandered, those who revile your good behavior in Christ may be put to shame (1 Peter 3:14-16; ESV)
Peter says that when we suffer for righteousness sake and we still live with hope, because we have allowed Christ to be Lord in our lives, then that is going to be reflected to the people around us. It will get people to talk, and they will ask, "Why do you have hope?" The way we live will be attractive to them and they will wonder how they can have a life like ours.
Apologetics and evangelism are important, but for many people those things will fall on deaf ears if the truth we present is not seen in the way we live. The way we live provides the necessary evidence that what we say is true. Our actions make our spoken words come alive.
If we are going to make disciples then we are going to need more than talking points and evidences, we are going to a need a life that shines a light in the darkness. We need to show people that what we say is true.