To live in sin means:

     to live according to the flesh: when we lived according to the flesh, then the sinful passions, revealed by the law, worked in our members to bring forth the fruit of death (Rom. VII, 5);

     to obey the lusts of the flesh: but put on our Lord Jesus Christ, and do not turn the care of the flesh into lusts (Rom. XIII, 14). - I say, walk in the Spirit, and you will not fulfill the lusts of the flesh (Gal. V, 16);

     to be in darkness: you were once darkness, but now the light is in the Lord; walk as children of light (Eph. V, 8). - If we say that we have fellowship with Him, but walk in darkness, then we lie and do not walk in the truth (1 John 1:6);

      The faithful must:

     hate sin: you who love the Lord, hate evil. He guards the souls of His saints; He delivers them out of the hand of the wicked (Ps. XCVI, v. 10). - Let love be unfeigned; abhor evil, cleave to good (Rom. XII, 9);

     flee from sin: fornication, and all uncleanness and covetousness, shall not even be called among you, as befits saints (Eph. V, 3).—And now lay aside all things: wrath, wrath, malice, slander, foul language in your mouth (Col. III, 8). - But the firm foundation of God stands, having this seal: the Lord has known His own; and let everyone who confesses the Name of the Lord depart from iniquity (2 Tim. II, 19);

     Turn away from sinners, that ye may escape their punishment: flee from the midst of Babylon, and save every man his own soul, lest he perish by her iniquity. For this is the time of vengeance with the Lord. He will repay him (Jer. LI, 6). - Let no one deceive you with empty words; for for this the wrath of God cometh upon the children of disobedience. Therefore do not be their accomplices (Eph. V, 6, 7).

The fatal fruits of sin:

      a) Sin makes prayer invalid: if I had seen iniquity in my heart, the Lord would not have heard me (Ps. LXV, p. 18). Whoever turns his ear away from hearing the law, to him also prayer is an abomination (Prov. XXVIII, 9). And when you stretch out your hands, I hide My eyes from you; and when ye multiply your supplications, I hear not: your hands are full of blood" (Isaiah 1:35). But we know that God does not listen to sinners; but whoever honors God and does His will, hearkens to him (Jn. IX, 31);