Let me say a few words about his doctrine of the authority of scripture.. This is a very important point insofar as it was the way in which, finally, biblicism developed in all groups of Protestant faith. The Bible for Calvin is a law of truth, and of course also a law of word. At length, that the truth might remain in the world in a continual course of instruction to all ages, he determined that the same oracles which he had deposited with the patriarchs should be committed to public records.
With this design the Law was promulgated, to which the prophets were afterwards annexed as its first interpreters. The Bible, therefore, must above all be obeyed. It contains a “heavenly doctrine.” This was necessary – although again an adaptation – because of the mutability of the human mind. This was the necessary way to preserve the doctrines of Christianity by writing them down, and making, as Calvin says, God’s instructions speaks of “the peculiar school of the children of God.” Now all this can be harmless, or can be the opposite, and there is much discussion going on as to how to interpret his doctrine of the Scripture. In any case the answer is that this doctrine is absolute, but it is absolute only for those to whom the Divine Spirit gives the testimony that this book contains the absolute truth. But if this is done, then we can witness to the whole Bible as an authoritarian book of a radically authoritarian character.
The form of the Biblical authority is derived from the fact that the Bible is composed under the dictation of the Holy Spirit. This term, “dictation of the Holy Spirit,” is something which produced the doctrine of verbal inspiration, in a way which surpasses anything which existed in Calvinism, and in contradicting the Protestant principle as such: t he disciples were “pens” of Christ; all elements which come from them were superseded by the Divine Spirit which testifies that in this book the oracles of God are contained. “Between the apostles and their successors, however, there is this difference – that the apostles were the certain and authentic amanuenses of the Holy Spirit, and therefore their writings are to be received as the oracles of God.” Out of the mouth of God” the Bible is written, I. e., the whole Bible; the distinction between the Old and New Testaments largely disappears. And you can find this still today in every Calvinistic country. Paul Tillich, A History Of Christian Thought – Table of Contents