"Ever since the Church began, this has been her method: the most fervent Christians - as Saint Ambrose said - joined together so as not to be displaced by the more lukewarm Christians. It is not necessarily the case that those who do not join with others are less fervent - someone may follow a more personal path. To be sure, nobody can avoid communionality, because this is the essence of the Christian fact!"Giussani, The Work of the Movement, 58
This is the dynamic of Christian life, although there are those who seek to limit the Church only to the fervent. These groups exist to edify the whole, so they should never attempt to segregate themselves from the life of the whole. In doing so, they inevitably become sectarian, and the children of these then become a new generation of nominalists.
The Church is in the world, and the world is also in the Church. Wheat and tares grow up together. As Isaiah proclaimed: "Your builders outstrip your destroyers, and those who laid you waste go forth from you."