There is emphasized in this attitude the believer’s continued sinfulness in fact and in act and his continued sense of his sinfulness. And this carries with it recognition of the necessity of unbroken penitence throughout life. The Christian is conceived fundamentally, in other words, as a penitent sinner.
We are sinners, and we know ourselves to be sinners lost and helpless in ourselves; but we are saved sinners, and it is our salvation which gives the tone to our life—a tone of joy which swells in exact proportion to the sense we have of our ill-desert. For it is he to whom much is forgiven who loves much and, who loving, rejoices much.
Throughout the Protestant world, believers confess themselves to be, still as believers, wrath-deserving sinners, and that not merely with reference to their inborn sinful nature as yet incompletely eradicated but with reference also to their total life manifestation which their incompletely eradicated sinful nature flows into and vitiates.
It has not always been easy through the Protestant ages to maintain in its purity this high attitude of combined shame of self and confidence in the mercy of God in Christ.
Thus, through every moment of his life, the believer is absolutely dependent on the grace of Christ, and when life is over, he still has nothing to plead but Christ’s blood and righteousness.
The believer strives against sin all his life and is never without failings. And from his well-grounded fear of sinning arises a powerful ever-present motive to watchfulness and effort. He has nothing to depend on but Christ, and Christ is enough. But that does not relieve him from the duty of cleansing his life from sin but rather girds his loins for the struggle. The necessity for the continuance of the struggle means, of course, the continuance of sin to struggle against.
~B.B. Warfield~
“Miserable Sinner Christianity,” Works of B.B. Warfield Vol. 7 (Grand Rapids, Michigan; Baker Book House; 2001) p. 113ff.