The Bible is against sin from cover to cover, and it is also an astonishing religious book in that it shows the frailties and failures of people that are of that faith. The first lie in the Bible is the lie that you can sin and not die spiritually. Why should the devil change a lie that people will so easily accept? How is it that that first lie and deception still runs rampant and is believed more than what God says about it?
But one must strain to 1 Jn. 1:8 to defend the devil and their sin. It is dealing with Gnosticism and Gnostics within the church that John is writing to. Verse 7 already states that Jesus Christ cleanses from ALL sin. How much sin is left if ALL is already cleansed? In verse 9, says if we confess our sins, he is faithful and just to forgive us ours sins, and to cleanse us from ALL unrighteousness. John's rhetoric by using "we" is to a mixed group, and in no way says that John or his Christian part of his audience ever said that they never sinned or had any sin to be cleansed of; but the Gnostics believed that! John no more is saying that Christians sin in verse 8 than he says in verse 9 where he uses "we", that their are Christians and he himself have never confessed their sins , had them forgiven and cleansed.
Take a step back to verse 7. The opposite is inevitable.... if you do not walk in the light as He (Jesus) is in the light, you do not have fellowship with one another, and the blood of Jesus Christ his Son does not [present tense] cleanse you!
The apostle John writes in his First Epistle, “My little children, these things I write unto you, that ye sin not.” (Gk, a singular act of sin.) (2:1). “And if any man sin” (not “when”). (2:1).., “He that saith, I know him, and keepeth not his commandments, is a liar, and the truth is not in him.” (2:4). “He that loveth his brother abideth in the light, and there is none occasion of stumbling in him.” (2:10). “Whosoever abideth in him sinneth not: whosoever sinneth hath not seen him, neither known him.” (3:6). “He that committeth sin is of the devil.” (3: 8). “Whosoever is born of God doth not commit sin;” (3:9). Notice that this does not speak of maturity, advanced sanctification, education, etc., it speaks of the grace to not sin occurring at the New-Birth. “Little children, let no man deceive you: he that doeth righteousness is righteous, even as he is righteous.” (3:7). “For whatsoever is born of God overcommeth the world: and this is the victory that overcommeth the world, even our faith.” (5:4). “We know that whosoever is born of God sinneth not; but he that is begotten of God keepeth himself, and the wicked one toucheth him not.” (5:18). “If we say that we have fellowship with him, and walk in darkness, we lie, and do not the truth.” (1:6). John says point blank that sinning, or walking in the darkness was incompatible with being a Christian. The same writer of 1 Jn. 1:8 could not say all the things he said against sin and not be the most self-contradictory writer in the Bible. But if we observe that First Chapter attacks the Gnostic beliefs, it is easy to avoid such contradiction and wrench 1 Jn. 1:8 out of its context to promote what the Bible everywhere says is not so.
The meager 4-5 twisted Scriptures that are thrown around as if they were the Gospel that defy every other passage in the Bible concerning sin, is why the Church is failing. God is against sin. The wages if sin is death. Jesus came to save His people from their sins, not in their sins.
The misapplied passages that people use to excuse their sin and still be a Christian reminds me of the story of when W.C. Fields was in the hospital a friend stopped by to see him. He was shocked to see W.C. Fields reading a Bible. Seeing the expression on his friends face he said, "I'm looking for loopholes!"