How does a believer when guilty of sin continue in a justified state? What does he plead before God?
Here is Owen's answer. The italicised sections are in the original.
"What is it that they betake themselves unto, what is it that they plead with God for their continuance of the pardon of their sins, and the acceptance of their persons before him?
Is it anything but sovereign grace and mercy through the blood of Christ? Are not all the arguments which they plead unto this end taken from the topics of the name of God, his mercy, grace, faithfulness, tender compassion, covenant and promises,--all manifested and exercised in and through the Lord Christ and his mediation alone?
Do they not herein place their only trust and confidence, for this end, that their sins may be pardoned, and their persons, though every way unworthy in themselves, be accepted with God? Doth any other thought enter into their hearts?
Do they plead their own righteousness, obedience, and duties to this purpose?
Do they leave the prayer of the publican, and betake themselves unto that of the Pharisee?
And is it not of faith alone?
...it is faith alone that makes applications unto grace in the blood of Christ for the continuation of our justified estate...our whole progress in our justified estate, in all the degrees of it, is ascribed unto faith alone."
Owen, Justification by Faith Alone, p. 148-9