Even the best of Christians can fall into sin, but there is great provision made when we do. We have an advocate, the Lord Jesus Christ, whose righteousness qualifies Him as the only one who can defend us before the Father.
1John.2.1-2My little children, these things write I unto you, that ye sin not. And if any man sin, we have an advocate with the Father, Jesus Christ the righteous: And he is the propitiation for our sins: and not for ours only, but also for the sins of the whole world.