This is a great little excerpt from Pilgrim's Progress which is my current loo-reading of choice. Christian and Hopeful are in conversation with Ignorance about where he stands with God. Ignorance has recently denied that his heart is bad.
IGNORANCE: Why, to be short, I think I must believe in Christ for justification.
CHRISTIAN: How! think thou must believe in Christ, when thou seest not thy need of him! Thou neither seest thy original nor actual infirmities; but hast such an opinion of thyself, and of what thou doest, as plainly renders thee to be one that did never see the necessity of Christ’s personal righteousness to justify thee before God. How, then, dost thou say, I believe in Christ?
IGNORANCE: I believe well enough, for all that.
CHRISTIAN: How dost thou believe?
IGNORANCE: I believe that Christ died for sinners; and that I shall be justified before God from the curse, through his gracious acceptance of my obedience to his laws. Or thus, Christ makes my duties, that are religious, acceptable to his Father by virtue of his merits, and so shall I be justified.
CHRISTIAN: Let me give an answer to this confession of thy faith.
1. Thou believest with a fantastical faith; for this faith is nowhere described in the word.
2. Thou believest with a false faith; because it taketh justification from the personal righteousness of Christ, and applies it to thy own.
3. This faith maketh not Christ a justifier of thy person, but of thy actions; and of thy person for thy action’s sake, which is false.
4. Therefore this faith is deceitful, even such as will leave thee under wrath in the day of God Almighty: for true justifying faith puts the soul, as sensible of its lost condition by the law, upon flying for refuge unto Christ’s righteousness; (which righteousness of his is not an act of grace by which he maketh, for justification, thy obedience accepted with God, but his personal obedience to the law, in doing and suffering for us what that required at our hands;) this righteousness, I say, true faith accepteth; under the skirt of which the soul being shrouded, and by it presented as spotless before God, it is accepted, and acquitted from condemnation.