“For whoever keeps the whole law but fails in one point has become guilty of all of it.” (James 2:10, ESV)
Many times as a pastor I would hear people excuse sin in their own lives or in the lives of others by saying, “Hey! No one’s perfect” or “I’m only human.” Those sorts of statements would suggest to me that such were immature in their faith and failed to grasp the seriousness of sin and the power of the gospel.
When James says, “whoever keeps the whole law but fails in one point has become guilty of all of it,” he is making it emphatic that no one is perfect in the sight of God and, more pointedly, because of that is liable to the judgment of hell.
I will sometimes cite James 2:10 when explaining the gospel (like here for a copy of the booklet, God's Good News). Rather than operating on a “’you’re only human’ and that excuses you,” basis, God operates on a “’you’re only human’ and your sin accuses you" basis.
God does not grade on a curve. He does not look at our life’s body of work and deem it worthy. Sin, any sin at all, serves as a leaven to the whole and makes us unclean before the all-knowing eye of a holy God. When the psalmist insists in the Old Testament and the apostle Paul affirms in the New Testament that all are corrupt and no one does good, not even one (Psa. 14; Rom. 3:10-11), he indicts every one of us. We are left without excuse.
The Spirit showcases our sin, however, not to drive us despair but to drive us to Christ. That is true for both our justification (standing before God) and our sanctification (living for God). Faith founded in Christ gains freedom from sin’s penalty and maintains freedom from sin’s power. That’s why James will go on to speak of salvation by faith alone but not by faith that is alone.
"Father in heaven, holy is Your Name. Help me to see the scope and seriousness and sordidness of sin in my life. Lead me to Jesus."