1. Not looking to get into a OSAS debate...really would derail the thread more, but I believe in OSAS, in part because of those very verses. I think, from reading your last post, you agree with OSAS, as do I.
2. It's a process. We must first realize that we are sinners, then must repent (that is, confess), and if God is willing, then we are Baptized (by Him in Spirit), and reborn. This is how I read John's Epistle, as the process and how to recognize the evidence of the saved. John makes several independent points in the first chapter
If we claim to have fellowship with him and yet walk in the darkness, we lie and do not live out the truth.
If we walk in the light, as he is in the light, we have fellowship with one another, and the blood of Jesus, his Son, purifies us from all[every] sin.
If we claim to be without sin, we deceive ourselves and the truth is not in us.
If we confess our sins, he is faithful and just and will forgive us our sins and purify us from all unrighteousness.
If we claim we have not sinned, we make him out to be a liar and his word is not in us.
Onto chapter 2
If anybody does sin, we have an advocate with the Father—Jesus Christ, the Righteous One.
Then to chapter 3
6 No one who lives in him keeps on sinning. No one who continues to sin has either seen him or known him.
See the process? See the transformation? What John is outlining here is the sanctifying work of the Spirit that dwells within the elect.
Otherwise, continuing in sin not only contradicts these verses, but to then say "While I still sin I am justified" is just like saying "I am licensed to sin, since none of it counts anymore." Just my .02.
@your last comment: All things are possible with God. We just have to faith enough to believe the Promise.