For those who will not settle for anything less than a perfect ChurchI would never think of leaving the Church because of the scandals that frequently occur in her midst. I've never much understood those who divide themselves from Mother Church because they want to form a more perfect one. The history of the Church is full of attempts to separate in order to live the Christian life more perfectly than those others. What these people find out is that they bring the very sinfulness that they are fleeing with them into their new situations.
One time my wife and I were considering joining a charismatic community. I remember at one prayer meeting one of the leaders went to the window of the room we were in and stuck out his tongue at the world. The implication was that we had somehow achieved moral perfection in that room because we had fully received the Holy Spirit and didn't want to be infected by the filth of the world. I made the decision right then and there not to join the group (also, because they seemed to neglect or marginalize the Church's social teachings). As the later unseemly history of another one of the group leaders showed, the filth of the world had not been exorcised from its members by the Holy Spirit.
Human beings are sinners before and after baptism. It couldn't please the devil more than to see divisions in the Church based on unreal expectations of each other. In the Screwtape letters Lewis talks about going to church with people who's sins we know. Screwtape tries to get Wormwood to get his subject to focus on the sins of the person in the pew next to him. Screwtape says something like, "Don't let him think about how much worse she would be if she WEREN'T a Christian."
The Church is a school of love. How can we learn to love unconditionally if everyone is perfect? Saint Therese of Lisieux (called "the Little Flower") lived in a community that has sometimes been labeled "dysfunctional," yet she used the imperfections of her community (not to mention her own) as a springboard for love and holiness.
One very important aspect of a loving community is unity. To divide because others aren't perfect is, I'd think, a grave sin. To stay is often painful, but to divide because of the sins of others accomplishes nothing but the splinterization of the Church.
Jacques Maritain wrote a book on the Church called On the Church of Christ in which he distinguishes between the person of the Church and its personnel. The person of the Church is Jesus Christ who is present in the Church and acts in the Church. Yet the personnel in the Church (and this notion can be extended to include all of us) do NOT in their every action manifest the acts of the PERSON of the Church. How do we distinguish? How do find the actions of Christ in the Church as opposed to the non-graced actions of the personnel?
In the end what do we come to Christianity for? To find s perfect society? To receive love? Or rather is it to receive the POWER to love, which we, and our fellow Christians, can learn to use (or not) after a long schooling full of failures? Love in Christianity is a potential that needs to be actualized. We all are given the grace to love, but we only imperfectly allow that grace to guide our activity.