Scripture isolated can cause all sorts of opinions and traditions to be put in place
Pay attention to the ..we and our and the you in 1 John chapter 1
"That which was from the beginning, which we have heard, which we have seen with our eyes, which we (believers - namely John ) have looked at and our hands have touched - this we proclaim concerning the Word of Life"
(I John 1:1).
In other words, John is establishing that he was an eyewitness to the fact that Jesus truly did come in the flesh. He did this to convince the Gnostics that Jesus was not an illusion.
"We ( believers - namely John himself ) proclaim to you (unbelievers - gnostics ) what we have seen and heard, so that you (unbelievers - gnostics ) also may have fellowship with us ( believers ). And our ( believers )fellowship is with the Father and with His Son, Jesus Christ" (verse 3).
This verse says two things. First, John repeats the fact that he, the rest of the apostles and other people saw Christ in the flesh. He wanted the Gnostics ( unbelievers ) to realize that there were many people who could testify to the reality of Christ.
Second, he is saying that there are some people in the audience who were not in the fellowship with Christ. ( just like we do now in all churches....there are both types of people )
"This is the message we ( believers ) have heard from Him and declare to you ( unbelievers ): God is light; in Him there is no darkness at all" (verse 5).
John's message in this verse is clear: God is light and in Him there is no darkness. We are either in the light (saved) or in darkness (lost). Scriptures are full of this comparison between light (saved) vs. darkness (lost).
"If we claim to have fellowship with Him yet walk in darkness, we lie and do not live by the truth." (verse 6).
In other words, if someone says he has fellowship with Christ, but is walking in darkness (lost), he is lying and not practicing the truth. The Gnostics ( not true believers ) claimed to be in fellowship with Christ (saved), and yet were actually living a lie and therefore weren't practicing the truth.
"If we ( believers ) walk in the light, as He is in the light, we ( believers ) have fellowship with one another, and the blood of Jesus, His Son, purifies us ( believers ) from all sin" (verse 7).
In other words, if we walk in the light (are saved) we have fellowship with one another and the blood of Christ cleanses us from all sin. To put it another way, once we are saved, we are permanently in the fellowship because the blood of Jesus continually cleanses us from all sin.
Therefore, we aren't forgiven because we confess our sins. We are forgiven because of what Christ did for us on the cross.
"If we ( John putting all of us in the same boat before coming to Christ ) claim to be without sin, we deceive ourselves and the truth is not in us" (verse 8).
John is now addressing the belief the Gnostics had regarding sin because they didn't believe it was real and therefore believed they had no sin. The "we" John is using here refers to all people before coming to Christ including all believers too which "we" had to acknowledge at some point in our lives.
He is referring specifically to the Gnostics, who believed they were without sin. Because they claimed to be without sin, then they were only deceiving themselves and the truth (Jesus) was not in them.
However, verse 9 says that "if we confess our sins, He is faithful and just and will forgive us our sins and purify us from all unrighteousness." In other words, if they..the Gnostics were to confess they had sins, then God, Who is faithful and righteous, would forgive and cleanse them from their unrighteousness.
In the Greek language, the words "forgive" and "cleanse" mean past actions that have results today and will continue to have results in the future. Also, the word "all" used in these verses means all. It doesn't mean that we are cleansed of our past sins and our past unrighteousness, it means we were cleansed of all our unrighteousness. And if God cleanses us from all unrighteousness, then we are cleansed forever!
"If we claim we ( all of us were in this boat at one time ) have not sinned, we make Him out to be a liar and His word has no place in our lives" (verse 10).
Basically this verse is a repeat of verse 8. To put it simply, it means that the Gnostics can't claim to be without sin and yet be saved. John is saying that because the Gnostics claimed they had no sin, they were actually calling God a liar and therefore didn't know the truth.
The purpose of the first chapter of 1 John was to compare the truth of God to the error of gnosticism. John was addressing the Gnostics, who were deceived by their own teaching. He wanted the Gnostics to understand that what they believed conflicted with what God said. He was not, however, addressing believers.