James 2:10 For whoever shall keep the whole law, and yet stumble in one point, he is guilty of all.

This verse shows you why everyone is a sinner.
No one has kept the Law to the max – except Jesus.
Everyone else has stumbled in a minimum of one point but probably more.
Perhaps you can stand before God and say, “I never killed anyone, I never committed adultery, and I never stole anything!”
That’s all fine and well.
However, you are not judged by the things you did not do but by those things you have done.
It is for this reason Jesus is the perfect substitute for you.
His perfection under the Law is condemned so your condemnation by the Law is perfected.
It’s a match made in heaven.