for all have sinned and fall short of the glory of God, (ESV)
I once pastored a church where there was a prominent member who had a fundamental problem with this verse. This woman sung in the choir, led committees, and kept a detailed history of the church. By all accounts she would have been considered by most to be a Christian woman. There was one problem. She claimed that she had never sinned. She did not need forgiveness.
This tragic example makes a very important point. All of a person's efforts at God's glory fall short. For this woman, her list of "church accomplishments" represented her standard of holiness. The problem is that her standard of holiness and God's standard of holiness were not the same. This is the case for anyone who attempts to be made right with God by human effort.
If you only committed one sin in your whole life that would be amazing. Yet, that one sin alone would be enough to condemn you before God's holy standard. Imagine that you have not only committed one sin, but rather, your whole nature as a human being is stained with sin. That is the reality for us all.
This concept of falling short of God's glory can be illustrated by an archer taking aim at a target. God's perfect target would have to be a bullseye. The archer carefully pulls the arrow back, judges the distance, and lets the arrow fly. Tragically, the arrow doesn't even reach the target. All of our efforts fall short. We must acknowledge our sin and allow God to offer his righteousness to us.
Those who will not admit their sin will die in it. The first step toward salvation is admitting that we fall short. "Church accomplishments" will not cut it. We have all sinned. Confess it.