Now here's the irony of Catholicism's elevating Rahner. Rahner's basic claim is that social/philosophical/theological thematization of the content of the faith is something secondary. It is, rather an objectification of an experience of the "Holy Mystery" which is the ineffable ground of being present within all humans. It is present to all human beings since all human beings possess divine grace as an existential (the so-called "Supernatural existential"). That is, it is part of their existence, while not beings part of their nature. It is the waters they swim in, so to speak.
Ok, so, the real sealing point of your system (Catholicism) is that you claim that you have the ability on an institutional level of mediating salvation. You claim you can do that through your institutions exclusively. So what do you do? You put a guy in charge of re-formulating your theology that says that cult, institution, and dogmatic formulation are secondary realities to the inner, individual, non-institutional experience of grace. Moreover, you put a guy in charge that says that divine grace is everywhere and therefore your institution may have the biggest concentration of it, but by no means has it exclusively. So, in other words, you decide to formulate your new theology in such a way that pretty much eliminates the major sealing points of your theology. Kinda a bad idea.
Hence the irony of Rahner. Rahner wants to make Catholicism more believable by ceasing to be Catholic. Lutherans can learn something by this example.