1 John 3:1-3 (ESV)
See what kind of love the Father has given to us, that we should be called children of God; and so we are. The reason why the world does not know us is that it did not know him.  Beloved, we are God's children now, and what we will be has not yet appeared; but we know that when he appears we shall be like him, because we shall see him as he is.  And everyone who thus hopes in him purifies himself as he is pure.
“The reason that the world does not know us is that it did not know him.” The world just doesn’t know Christians. Oh the world, the people of the world, they know Christians in a sense, in the same way one might know a coworker at the office, but not the way one knows a family member, or a friend they have grown up with. The world just does not know Christians. You see it day in and day out in popular media, very rarely is there any real insight into what it means to be a Christian, why we are who we are, and do what we do. Too often, what the church does is treated as something that should be up for popular vote. That we should determine our morals in the same way as the world does, by determining what is popular. But Christians are held captive to the word of God, to the scriptures.
Yes the scriptures have been abused through the years by the church. They have been used to justify things that are not justifiable. They have been ignored at times and not brought to the fore to argue against things that should have been argued against. And in this way the church looks like a group of hypocrites, when in fact they are just sinners. Now if they intentionally ignore, they might be hypocrites or hypocritical. I have found that that is true of most people Christian or not. It is a byproduct it seems of our sin, that we also end up hypocrites. Yet the Christian will be convicted by scripture. He will recognize and repent of sin when shown its sinfulness. But the Christian will never be without sin until the appearing of Christ. We live with that even as we fight against it.
We don’t need to be sinless ourselves to identify sin, to convict of sin. It is not us who determine what a sin is or isn’t, but the word of God. In this way the word of God always serves as a corrective in Christian societies. It can be that for generations a sin is more or less tolerated, but then when reading scripture the Bible brings conviction that something is wrong there is change. The issue of slavery is very much a case in point. Even though a case could be made from the Bible to tolerate slavery, there is a better case to be made that as Christians we should not tolerate the abuse of people, the devaluing of people that is all but inherent in the institution of slavery. Over time the love of God that causes us to be called Children of God prevailed in society and put an end to slavery. (Well how much an end is to be debated, but.)
So it is also with the individual Christian. We work to purify ourselves even as we are pure. Forgiven of our sins we work to rid ourselves of sin. Our battle against sin is not one in which we have to overcome sin. But that Christ has overcome sin and forgiven our sins already, we are sickened to sin. The new man in us wishes to purge ourselves of sin. The Holy Spirit working upon us through the word of God is constantly convicting us a new of sin, and working to rid ourselves of it. Even recognizing sin as sin is so much the beginning of this, and grace abounds, because there is no overcoming of sin apart from the grace of God, who has overcome sin.