Let me know when you attain sinless perfection in your life, and then tell me your secret. The rule is that you need to love the Lord with all your heart, soul and strength, one small lapse in that will scupper your sinless perfection. Also, just one thought that when you get pretty close to perfection you start to think, "I'm doing pretty well right now" is the sin of pride and that kills your sinless perception stone dead. We can sin without realising it, because there are not only outward behavioural sins, but there are sins in the heart. The very fact that you might have fellowship with only those believers of your own religious denomination or theological view, is a party spirit which is a sin as well. So, how does your sinless perfection stack up against those things?
It is not a sin to not fellowship with, say, mormons; because the Bible tells us not to fellowship with the unfruitful works of darkness (Ephesians 5:11).
And while I most certainly attend a Calvary Chapel and tend to fraternize with people who go to my church, this in no way means that I will not fellowship with, say, a Methodist.
Now consider Galatians 3:14 and Romans 5:5.
Through faith, the love of the Lord is shed abroad in the hearts of those who belong to Him because of the Holy Ghost who has come to dwell within us.
This is the fruit of the Spirit; and against such there is no law (Galatians 5:22-23).
Because I bear this fruit, I have a righteousness of God that is apart from the law that is nevertheless attested to by the law and the prophets (Romans 3:21) that it is righteousness indeed. This is practical righteousness on the same level as Jesus Christ is righteous (1 John 3:7).
This is the righteousness of faith (Philippians 3:9) and yet it translates into the righteousness of the law being fulfilled in me (Romans 8:4).
It is not that I keep the law perfectly (Galatians 6:13)...such as wearing tzitzit and tallit and tefilin or blowing the trumpet on the new moon...
But I have been delivered from the law so that I might walk in newness of the spirit and not any longer in the oldness of the letter (Romans 7:6).
This amounts to walking not after the flesh but after the Spirit (again, Romans 8:4).
In doing so, the righteousness of the law is fulfilled in me (above verse).
And since sin is the transgression of the law, I cannot sin in such a state (when I am walking not after the flesh but after the Spirit)...because if the righteousness of the law is fulfilled in me, then I am not doing anything in violation of the spirit of the law.
Again, this is because I bear the fruit of the Spirit and there is no law against bearing such fruit (Galatians 5:22-23).
Therefore, in bearing the fruit of the Spirit, I do not transgress the law; and since sin is the transgression of the law, this means that I do not sin.
For sin has now been re-defined as walking after the flesh (Romans 8:4); and as anything that is not of faith (Romans 14:23).