I thought it would be interesting to see how Karl Barth sketches Immanuel Kant’s understanding of the relationship between [biblical] theology and philosophy; you might be 
surprised. What is interesting to me is to see how closely Barth’s development of Kant’s thought here mimics Barth’s own approach towards an understanding of the relationship between theology and philosophy.[1] We will hear from Barth at some length and then close with some concluding thoughts (per my usual format for blog posts):
Kant, as we have seen, with the notion of the Church as his starting point, pondered the possibility of the Bible having a position and significance, which, even if it were not ‘divinely statutory’ would yet be extraordinary and qualified, and he went on from this to ponder also the possibility of a theology which would be different from the philosophical theology he himself was propounding. He explicitly calls this other theology, which limits philosophical theology, ‘biblical theology’, and it is his with that the affairs of this biblical theology should not ‘be allowed to mingle’ with those of philosophy. He wants rather to form for it a definite distinct idea as befits its own peculiar nature. For Kant the possibility for such a discipline or faculty, which is theological in the narrower and specific sense, is given, first of all formally, simply with the existence of the Church which has its foundation in the Bible. Philosophy would be exceeding its rights if it were by any chance to proceed to the formation of a Church, to a special philosophical preaching, on the basis of its own understanding of religion. Philosophy does not offer itself as a rival to theology, but as a ‘friend and companion’. ‘A minister of a Church is bound to convey his message, to those he is teaching the catechism, and to his congregation, according to the symbol of the Church he is serving.’ Kant disputes the idea that a minister’s task as an office-holder is dependent upon any historical-philosophical convictions he might hold as one learned in the subject. A preacher would be bound to abandon his office for this reason, only if he should find something flatly in contradiction of the ‘inner religion’, as he must understand it as a philosopher, in the teachings of his Church, but not if these teachings do not happen to correspond exactly with his historical-philosophical convictions. Even if such a conflict between the office-holder and the scholar in him should take place, the scholar can always explain that it is not completely impossible for ‘truth to lie hidden’ in the things he has to represent in the Church as one holding office.
And with this we have arrived already at what, according to Kant, constitutes the material possibility of a biblical theology. Kant guards against the reproach that it seems as if his critical religious teaching is presuming to dispute revelation. This is not his intention, ‘since it might be after all, that the teachings of revelation stem from men supernaturally inspired’. He does not wish to assert that in matters of religion reason is sufficient unto itself, but acknowledges (let us think once again at this point of that letter to Jung-Stilling) that reason, after it has established in religion those things which it is fitted to establish as such, ‘must await the arrival of everything else, which must be added beyond its capacity, without reason being permitted to know in what it consists, from the supernatural helping hand of heaven’. ‘Even at that point where philosophical theology seems to accept principles in opposition to those of biblical theology, e.g. in respect of the teaching concerning miracles, it confesses and proves that it does not assert them as objective principles, but only as subjective ones; they must, that is, be understood as maxims, when we merely wish to make use of our own (human) reason in judging of theological matters; and in so doing we do not dispute the miracles themselves, but merely leave them without restraint to the biblical theologians, in so far as he wishes to judge solely as a biblical theologian and scorns any alliance with philosophy.’ What Kant does dispute is the idea that the reality and possibility of revelation, its availability as data for human reason and its perception by human reason, are things which can be accounted for by philosophical means, the idea that over and beyond the philosophy of religion there is a philosophy of revelation and of faith, and that by its theology might be represented, or make its position secure. At the same time, however, he disputes the philosopher’s right to deny revelation because it cannot be accounted for by philosophical means. He therefore advises both the theologian and the philosopher ‘not to indulge his curiosity in those things which do not pertain to his office and of which in general he understands nothing’. For him theology is a ‘privileged body’, which he quite plainly instructs to do precisely those things in matters of religion which philosophy dare not do, and to refrain from doing precisely those things which philosophy is bound to do.
What may theology not do? It may not ‘interfere in the free profession of philosophy and attempt to prove or refute its principles of belief least of all, by philosophy’, just as philosophy for its own part has to resign itself that it cannot pass any definitive judgment upon the authority and exposition of the Scriptures. Theology ‘does not speak according to the laws of the pure and a priori knowable religion of reason, for in so doing it would debase itself and set itself down upon the bench of philosophy’. It may not, ‘in what concerns the fulfillment of the divine commandments in our will . . . by any means count upon nature, upon man’s own moral capacity (virtue), that is’. The interpretive method of ‘giving another meaning to something’ is forbidden for theology: theology cannot be entitled ‘to give the sayings of the Scripture a meaning which does not exactly suit what is expressed in them; with a moral meaning, for instance’, ‘and since there is no human expounder of the Scripture authorized by God, the biblical theologian must rely upon a supernatural enlightenment of the understanding by a Spirit which guides into all the truth, rather than concede that reason intervenes’. ‘The biblical theologian as such cannot and may not prove that God himself spoke through the Bible, since this is a matter of historical fact, and thus belongs to the philosophical faculty.’ He must, as Kant at one point says, certainly not without malice, as a pure (purus, putus) biblical theologian, be ‘still uninfected with the accursed free spirit of reason and philosophy’. What, on the other hand, should theology do? The answer: ‘The biblical theologian is really the scribe of the Church faith, which rests upon statutes; laws, that is to say, which stem from the arbitrary choice of another authority.’ Theology ‘speaks according to statutory prescriptions of belief which are contained in a book, preferably called the Bible; contained, that is, in a codex of the revelation of an Old and New Covenant of men with God, which was joined many hundreds of years ago, and whose authentication as a historical faith (and not, particularly not, as a moral faith, for that might also be drawn from philosophy) should surely be expected from the effects of the reading of the Bible upon the human heart rather than from . . . proofs’. ‘The biblical theologian proves that God exists by means of the fact that he has spoken in the Bible.’ He may, in the question of the realization of the will for good, count only upon grace, ‘which, however, man cannot hope to partake of in any other way than by virtue of a faith which fervently transforms his heart; which faith itself he can, however, in his turn expect of grace’. Theology, with these premises it has: the Church, the Bible, historical revelation, and grace, should allow itself to be ranked together with other branches of learning and content itself with the influence it can acquire as such by its own dignity.[2]
I don’t want to say too much because this post is already starting to run long, and I want you to read what Barth has written of Kant here. But if you are aware of Barth’s theology you’ll recognize some of the ethos of Kant’s thinking (as reported by Barth) in Barth’s own mode. Of course, as we noted in a recent post, Barth could not live with the dualism that Kant operated from and thus reified such thinking by taking Kant’s dualistic thinking (as evinced by his rupturing of the ‘knowledges’), and declawing that in the union of God and humanity in the hypostatic union that occurred in Jesus Christ; such that the objective and subjective aspects of knowledge are brought together in the singular person known as Jesus of Nazareth.
Nevertheless, what Barth offers us here, in sketch, I think provides an interesting look into Kant’s thought vis-à-vis Barth’s. Further, it is interesting to take Kant’s duality and apply that to what happened to the disciplines of theology and biblical studies in the 18th century (and into the present); it’s ironic that biblical studies, as a discipline, actually traversed Kant’s ‘lines’ and instead began developing its systems based upon the grounds that Kant would reserve for the philosophers; thus ‘de-confessionalizing’ the Bible and its study by placing it on a naturalist trajectory.
[1] For an in depth analysis of this locus in Barth see Kenneth Oakes most fantastic book: Karl Barth on Theology&Philosophy (OUP).
[2] Karl Barth, Protestant Thought: From Rousseau to Ritschl (New York, New York: Simon and Schuster, 1969), 192-95.