The understanding of the sinfulness of man helps us in evangelism. More specifically, understanding our own personal sinfulness helps us in evangelism.
Romans 3 : 23 says, "For all have sinned and fall short of the glory of God." We're all sinners, we all are in desperate need of a Savior.
My biggest stumbling block is realizing the magnitude of my own sin. I have no problem recognizing sin in the lives of others, but have an extremely difficult time taking my own sin seriously.
Sin is not just murder, it is not just adultery. It's also the little white lies, it's also gossip. The Bible says "all wrongdoing is sin" (1 John 5:17) and "anyone who knows the good he ought to do and doesn't do it, sins" (James 4:17). Sin is much broader than we tend to think!
If you're like me, it helps to use an analogy. In terms of archery, to sin is to miss the bulls eye. Anything other that a bulls eye, even if you hit the target, is a sin. Anything we do in our own power, without God, is sin! In Isaiah, The Lord describes even our most righteous deeds as menstrual rags when done apart from him.
But here's the good news of the Gospel, when we confess with our mouths and believe in our hearts Jesus as Lord, we are saved (Romans 10:9).
How does knowledge of sin helps in evangelism?
- It levels the playing field. The sharer of the Gospel needs a Savior just as much as the hearer.
- It keeps us humble. It is written "For by grace you have been saved through faith. And this is not your own doing; it is the gift of God, not a result of works, so that no one may boast" (Ephesians 2 : 8-9 ESV). Because of our sinfulness, we wouldn't even be able to accept the truth of the Gospel without God giving us the faith to believe it. I have to remind myself that I literally had nothing to do with God rescuing me. God gave me the faith to confess and believe, I didn't muster it up on my own.
- It keeps us from self-righteousness. This goes hand in hand with keeping us humble. When we realize what sinners we are, we are far less likely to judge our neighbor. We don't become the man with a plank in his eye trying to remove the speck from his neighbors.
- It overwhelms us with thankfulness. When we realize what God saved us from, we want to worship Him! Not only that, but we want to share what He's done for us with others. When we understand our own depravity, it not only helps us evangelize, it gives us the desire to.