John's epistle was written to those who were being infiltrated by what we call Gnostics. They would live in sin yet refuse to call their actions sinful. John saw that it was a lie holding them in bondage. He knew that before you can come to a place where you stop sinning, you must confess that you have sinned; you must confess it so that God can cleanse you.
Whenever someone (Not addressed to anyone in particular) takes a scripture out of Bible and says it was NOT addressed to us but someone else, so let us ignore it, I seriously doubt whether that person is even Born again. That is why I never perused arguing with such people though they keep pulling my leg many times, to me arguing with such people is like arguing with blind men about color. They neither can see it but will keep holding to something about color that they have heard in the past. Same way such people will hold theology more than scripture.
Read 1 John 1:8 again, "If WE say that we have no sin, WE are deceiving ourselves and the truth is not in us." Note the term WE which means even the apostle is also addressed in that verse. Plus it is not about the past sins but about the present sins. He did not say 'we HAD' but he said 'we have', clear use of presentance here. Which means Sin existed even in Apostle John and also in the Church to which the letter was addressed.
Let me give an explanation that will not be against any scripture. In 1 John 1:8, John is talking about unconscious sins. When we are born again we get light on our sinful nature, but we do not get light on all our sins. It is like feeding babies with milk instead of solid food, because the baby is not in a position to digest it(Hebrews 5). Only those that we know sins we repent and set things right. We are expected to walk by Spirit and not flesh and overcome all known sins. At anytime, our conscious should always be clear before man and God (Acts 24), in other words there should be no un-repented sins in our life that we are aware of. This can be compared to a 1 grade student getting 100% in mathematics, this does not mean the student is an expert in Mathematics and can challenge any Maths Scholar. But it only means that whatever was taught to this kid in 1st grade under mathematics, this kid is perfect in it.
As we overcome the conscious sins, God will give us light on the unconscious sins in our life. This is like this Kid getting into 2nd grade, where he will get exposed to multiplication, division etc. Same way God will also show light in areas of our life where we thought Sin never existed. This way our growth towards Christlikeness will be gradual (Gradual Sanctification). But at any instant we are not to consider Sin lightly. Anything that we know is sin, should be hated by us.
A practical explanation is something like a man who initially comes to Christ knows if he shouts in anger towards anyone he has committed murder. Later when he overcomes this, God will show him that he still has bitterness in his heart towards others which is also same as anger. Now he repents from that as well. In future God will show him something like any unforgiven thought that he entertains is a sin. So the more he matures in his Christian walk he identifies more sins in his walk and he repents of them.
This is why Apostle Paul writes in 1 Corinthians 4:4 - "For I am conscious of nothing against myself, yet I am not by this acquitted; but the one who examines me is the Lord." Though Paul did not have any known sin, he acknowledges that he does not considers himself righteous, because God who judges him knows the true condition of him. This is what it means in Philippians 3:12 when he says he does not consider himself perfect.
Regarding verses like 1 John 3:22, where it says we should not have any sin that is condemned in our heart, these are sins that we are conscious about. John says that if we have conscious sins in our life then we cannot have boldness before God.
I really appreciate the post from our moderator in another thread to a person holding similar theology who was accusing a 'man of God' who has most sermons on this sight. Moderator gracefully asked that poster to go to other website and post if you consider yourself much holier and cannot accept such preachers.
When Lucifer was kicked out of Heaven he gathered a part of angels towards him to rebel against God. A true person living for God, if asked to leave a place, will leave without making any noise. Jesus when was asked to leave Gerasenes by the men in that region, he left without making any noise (Mark 5-17). This shows the difference between the spirit of Lucifer and Jesus.