Ezekiel 33:12
Therefore, thou son of man, say unto the children of thy people, The righteousness of the righteous shall not deliver him in the day of his trangression: as for the wickedness of the wicked, he shall not fall thereby in the day that he turneth from his wickedness; neither shall the righteous be able to live for his righteousness in the day that he sinneth.
James 2:10
For whosoever shall keep the whole law and yet offend in one point, he is guilty of all.
Hebrews 10:26,29
For if we sin willfully after that we have received the knowledge of truth, there remaineth no more sacrifice for sin.
See Hebrews 9:22,14--i.e. If Salvation is a pardon for sin, brought about by the death of Jesus Christ (the shedding of his blood, thus the "blood of Christ" and "sacrifice") we receive the pardon when re repent of our sin and allow Christ into our lives. This scripture points out a warning, however, that if we sin after having been covered by the blood or sacrifice of Christ for our sin, there remaineth "no more sacrifice!" If you sin "willfully" after have received forgiveness, you have cancelled the sacrifice, and it does not remain any longer. Now, you must repent and be forgiven anew.
1 John 3:4,6,8-10
Whosoever committeth sin trangresseth also the law: for sin is the transgression of the law. Whosoever abideth in him sinneth not: whosoever sinneth hath not seen him, niether known him. Whosoever sinneth is of the devil. Whosoever is born of God doth not commit sin. . .whosoever doeth not righteousness is not of God.
Luke 9:62
No man, having put his hand to the plow, and looking back, is fit for the kingdom of God.
1 John 5:18
Whatsoever is born of God sinneth not; but he that is begootten of God keepth himself, and that wicked one toucheth him not.
Amos 3:3
Can two walk together except they be agreed?
The prophet is posing a rhetorical question with a clear, unequivocal answer: No they cannot. How then can YOU walk with the Devil, and be the servant of God? If you "walk" in sin, you are "agreeing" with the Devil. Christ himself said that a person is either for him or against him. There is no middle ground. Therefore, anyone walking with Devil is not a servant of God. See Romans 6:16 below.
Luke 16:13
No servant can serve two masters; for either he will hate the one and love the other; or else he will hold to the one, and despise the other. Ye cannot serve God and mammon.
Romans 6:16
Know ye not that to whom ye yield yourselves servants to obey, his servants ye are to whom ye obey; whether of sin to disobedience, or of obedience unto righteousness?