Job Was Not Without Sin
But let us see what Job has to say of himself, after God's great testimony of his righteousness. “I know of a truth,” he says, “that it is so: for how shall a mortal man be just before the Lord? For if He should enter into judgment with him, he would not be able to obey Him.” And shortly afterwards he asks: “Who shall resist His judgment? Even if I should seem righteous, my mouth will speak profanely.” And again, further on, he says: “I know He will not leave me unpunished. But since I am ungodly, why have I not died?
If I should wash myself with snow, and be purged with clean hands, you had thoroughly stained me with filth.” In another of his discourses he says: “For You have written evil things against me, and hast compassed me with the sins of my youth; and You have placed my foot in the stocks. You have watched all my works, and hast inspected the soles of my feet, which wax old like a bottle, or like a moth-eaten garment. For man that is born of a woman has but a short time to live, and is full of wrath; like a flower that has bloomed, so does he fall; he is gone like a shadow, and continues not.
Have You not taken account even of him, and caused him to enter into judgment with You? For who is pure from uncleanness? Not even one; even should his life last but a day.” Then a little afterwards he says: “You have numbered all my necessities; and not one of my sins has escaped You. You have sealed up my transgressions in a bag, and hast marked whatever I have done unwillingly.” See how Job, too, confesses his sins, and says how sure he is that there is none righteous before the Lord.
So he is sure of this also, that if we say we have no sin, the truth is not in us. While, therefore, God bestows on him His high testimony of righteousness, according to the standard of human conduct, Job himself, taking his measure from that rule of righteousness, which, as well as he can, he beholds in God, knows of a truth that so it is; and he goes on at once to say, “How shall a mortal man be just before the Lord? For if He should enter into judgment with him, he would not be able to obey Him;” in other words, if, when challenged to judgment, he wished to show that nothing could be found in him which He could condemn, “he would not be able to obey him,” since he misses even that obedience which might enable him to obey Him who teaches that sins ought to be confessed.
Accordingly [the Lord] rebukes certain men, saying, “Why will you contend with me in judgment?” This [the Psalmist] averts, saying, “Enter not into judgment with Your servant; for in Your sight shall no man living be justified.” In accordance with this, Job also asks: “For who shall resist his judgment? Even if I should seem righteous, my mouth will speak profanely;” which means: If, contrary to His judgment, I should call myself righteous, when His perfect rule of righteousness proves me to be unrighteous, then of a truth my mouth would speak profanely, because it would speak against the truth of God.
Source: Merits and Remission of Sin, and Infant Baptism (New Advent)