When one considers theology as a whole one may distinguish between two moments: the simple listening to God’s message and the systematic elaboration of what has been heard under formal points of view. In speaking of theology in Hearer of the Word, Rahner has meant the former. Yet this theology, he says, this hearing, requires a hearer; there would exist no word of God if there were not someone who would at least be capable of perceiving it. Hence there exists a theological anthropology. The listening presupposes not only a basic human makeup (i.e., the capability of hearing) but also a listening in freedom, a willing accepting of it. This Rahner calls a fundamental theological anthropology, which is the authentic philosophy of religion.
This philosophy of religion is first of all philosophy because it starts from the nature of humanity, under formal principles of thinking, using the natural light of reason. But insofar as it deals with the nature of humanity as spirit, it comprises a metaphysical anthropology. This philosophy of religion will always be a fundamental theological anthropology whose last word is the summons to listen for God’s word.
Yet it remains limited. Contra Hegel, Rahner asserts that whatever this philosophy of religion may discover, with the natural light of reason, about human religion, it must be (and has been) superseded by revealed religion. This philosophy of religion cannot force theology, or deduce it, or impose laws upon it. But it shows us as beings who can listen, should God’s Logos come into this world. It prepares for theology, it is its presupposition.
In fundamental theology the problem was how we human beings could be the recipients of such revealed knowledge without being entitled to demand it as the necessary end of our immanent development. The answer is that, on one hand, we indeed are spirits capable of listening for we have an absolute openness upwards for all being; on the other hand, real infinity is never presented to us as actually reached, but always only as the ever greater beyond of our knowing. We know infinity only through negation (even the word “in-finity” is the negation of finiteness), for we are finite. Knowledge of infinity is analogous and always an anticipation. We stand before God as before the one who is and forever remains free.
In Christian philosophy the question was how it can be Christian. The answer is that philosophy as real philosophy is Christian because as fundamental theological anthropology, it “sublates” itself into theology, as it makes us listen to the possible revelation of God. Correctly understood, philosophy is always an expectation, a preparation for the Gospel.
Finally, Rahner’s philosophy of religion synthesizes the problem of the two main types of Protestant philosophy of religion. In the Schleiermacher/Ritschl tradition the content of religion is merely the objectivation of the religious conditions of the human subject, as an experience of value, a feeling of ultimate dependence, an awareness of justification, and so on. God is the inner meaning of the world and of humanity and nothing more. In the Barth/Brunner tradition, the content of religion is the word of the living God as it sovereignly judges all that is finite and human, and God is the one who utterly contradicts us and our world.
But Rahner argues that revelation is more than the mere objectivation of humanity’s subjective state, and at the same time revelation is not the dialectical correlate of humanity as we remain caught in our finitude. It belongs to our essential makeup a positive openness for an eventual revelation from God. Revelation does not have to be merely a critical judgment pronounced on what is human, merely something standing above the world, which can never become “flesh.” Yet, on the other hand, we can and must accept God’s free revelation as unexpected, undue grace in history – not as opposed to nature, but as standing above nature.