The Ark can be understood as a singular universal. In the history of philosophy we see the paradoxical yet seemingly necessary concept of singular universality as productive engine sparking reflection, debate and new theories. The basic problems is this: we are inclined to associate abstraction with generality (‘types’ of things, which are immaterial, apply to a plurality of concrete entities) whereas we associate concreteness with singularity (there’s only one unique instance of anything real, like the candle burning next to me as I type).
Yet it is possible to conceive of singular abstract entities, and may even be necessary; but once we do this, may questions arise. The singular universal seems both necessary and impossible: a paradox. This is the essence of Aristotle's critique of Plato's conception of form, and in particular Plato’s belief that the forms are more real than the material entities to which they apply. But how can forms be at the same time universal (they are predicates in which individuals participate) and singular (there is 'one' of each, each one really exists)? If forms are singular entities, than each form must itself belong to other forms, and those must belong to others, ad infinitum. This, to Aristotle, is an absurdity. He rejects the reality of the forms and posits that primary substances must exist, which can receive and pass through various forms. Only these primary substances interacting in a spatiotemporal matrix are real and fully individuated; forms are secondary and they never have singular existence. But Aristotle’s account has its own problems, one of which is the question of all things. Is the world as a whole a form or a substance? If it’s a form, it isn’t real. But if it’s a substance, how is it that it also plays the role of form, given that the world as a whole surely must in some sense be the most general type, the collection of everything (what else would it be?)
It is this inability to convincingly posit either the singular or the universal as fundamental, the absolute point at which the distinction between form and substance breaks down, that finds a paradoxical fulfillment in Jesus Christ. As explicated by Von Balthazar, Christ is the singular universal itself: a fully adequate representation of God expressed in an individual, incarnate being (God as form, Christ as substance). Jesus Christ solves the paradox at the limit of the distinction between form and substance by simply designating its paradoxical quality and declaring it as unique.
There is a certain danger in poststructuralist attempts to 'abstract' this notion of Christ into a more general 'enigmatic' signifier that signifies only itself. As soon as we turn Christ into a special signifier, his singularity is re-universalized, because he becomes a type of signifier. There can be as many enigmatic signifiers as we want. But if there are more than one, we return to the logic we were seeking to escape.
The enigmatic signifier needs to have a proper name (a rigid designator). Jesus Christ is a good one, though there are other good candidates as well. Why Christ only? Why not the enlightenment? Why not the philosopher's stone of hermeticism? Or the birth of language itself?
Maybe it’s best to simply call it "Ark". "Ark" names something that has truly already happened (something along the lines of the incarnation of the word) which authorizes hope for the perfect fulfillment of human desire and calls for asceticism, suffering and transfiguration.