To see in Catholicism one religion among others, one system among others, even if it be added that it is the only true religion, the only system that works, is to mistake its very nature, or at least to stop at the threshhold. Catholicism is religion itself. It is the form that humanity must put on in order finally to be itself. It is the only reality which involves by its existence no opposition. It is therefore the very opposite of a "closed society". Like its Founder it is eternal and sure of itself, and the very intransigence in matters of principle which prevents its ever being ensnared by transitory things secures for it a flexibility of infinite comprehensiveness, the very opposite of harsh exclusiveness which charactarizes the sectarian spirit... The Church is at home everywhere, and everyone should feel himself at home in the Church. Thus the risen Christ, when he shows himself to his friends, takes on the countenance of all races and each hears him in his own tongue.
-Henri Cardinal de Lubac, Catholicism : Christ and the Common Destiny of Man
This is one of my favorite quotes in Catholic theology, and I think it best exemplifies the call to universalism to which only the Roman Catholic Church can truly respond.
There is a danger in many circles to mistake certain traditions for things that are given universally at the point of the propagation of the Apostolic tradition. It seems that many would have a certain age, phraseology, or style of art as constitutive of the essence of Christianity. For de Lubac, such prejudices are untenable. There are not certain times where the ethos of Christianity is entirely under the assured guidance of the Holy Ghost, and other times when the Holy Ghost abandons average Christians to their own devices. The wrestling between Divine Grace and human nature is a constant phenomenon that requires discernment on our part as thinking Christians. There is no point in apotheosizing one part of our past while rejecting another.
There is also a temptation to read more into certain parts of the past than is actually there. Again, I must posit again my simple formulation of the essence of historical romanticism: to read into the past agendas of which our ancestors were unaware. Our own crises of meaning in postmodernity do not give us license to manipulate the past to our own whims, nor can we pit the past against the present for our own purposes. It is in the here and now that the Church is made, built primarily on the foundations of our immediate past.
Otherwise, what we will do as Christians is to make the Gospel into an ideology. And ideologies do not open the mind and the heart, they close them. And to be open, to be truly Christian and human, is to remain open. The key to this is the philosophical tool of mercy. We must look on historical and cultural situations not to judge them in the ways in which they fall short, but rather on how they can be used as vehicles of grace. And we must refuse to squeeze things into boxes, even if this means that we must think and define things rather sloppily. That is the essence of Catholic thinking. It is not ready made, it cannot be fit into neat slogans, and it will always look unpolished and unfinished. But that is the first step to our transformation in Christ.