As a partial response to the question about the theology of Paul Tillich I would like to cite here from the book of Avery Dulles “Catholicity of the Church”.
In recent years it has become commonplace to contrast the Catholic substance of Christianity with the Protestant principle. Paul Tillich especially popularized this polarity. By the Catholic substance he meant the embodiment of the Spiritual Presence in holy persons and institutions, in word and sacrament. By the Protestant principle he meant the critical or prophetic mandate to protest against any claims to divine dignity made on behalf of these embodiments. Tillich’s point of view, as we shall see, had its basis in a whole line of Protestant thinkers beginning with Hegel and Schelling. Lutherans of our day, such as Jaroslav Pelikan and George Lindbeck, continue to warn that the Protestant principle is. needed to prevent Catholicism from becoming ossified, magical, demonic, and idolatrous.
At an informal dialogue with Professor Lindbeck at Gettysburg Lutheran Seminary in 1980, Professor Carl Peter asserted the necessity of admitting not only a Catholic substance but a Catholic principle. His point, as I understand it, was that unless the substance is protected by a principle it will gradually be eroded by a criticism that does not know where to stop. As one formulation of the Catholic principle he proposed: ‘Be not so prone to expect abuse that you fail to recognize God’s grace as working, as having worked, and as hopefully going to work again’ through the means that have been given. The Catholic principle, he went on to say, prevents one from calling sin what God has made clean (cf. Acts 10: 14). It enables one to hear the command, ‘Put off your shoes from your feet, for the place upon which you are standing is holy ground’ (Exod. 3: 5). The Catholic principle thus keeps Christianity, whether Protestant or Catholic, from falling into sins of irreverence, scepticism, and sacrilege, which are no less deleterious than magic, superstition, and idolatry.
Reflecting on this recent development in ecumenical discussion, I would be inclined to speak of a Christian substance and of two principles. The Protestant principle, as a critical norm, prevents one from blurring the distinction between God and creature and from attributing divine status to that which is finite and defectible. The Catholic principle, conversely, criticizes the critics. It warns them not to banish God from his creation and not to minimize the gifts of God in Christ and in the Holy Spirit.
The Catholic principle is an acceptance of mediation, and indeed of visible mediation. It asserts that God ordinarily comes to us through the structures that are given, especially those to which his gracious promises are attached, such as Incarnation, Scripture, sacrament, and apostolic ministry. The first attitude of the believer toward Christ, the Bible, the Church, and tradition ought not to be one of suspicion but, on principle, one of trusting receptivity. If it later appears that there are reasons for suspecting that the mediation has been faulty, the time will come for criticism and even protest. But if criticism comes too early it can be corrosive of faith.
The concept of a Catholic principle is not a new invention.
When Johann Adam Möhler in 1825 wrote his masterful work, Unity in the Church, he gave it the subtitle, ‘The Principle of Catholicism’. For the young Möhler the Catholic principle signified the quasi-organic unity brought about by the abiding presence of the Holy Spirit in the Church as a whole and in all its parts. Möhler stressed that the Holy Spirit, as divine reconciling principle, blends the differences among the members into a rich, diversified harmony. In his later work Möhler gave greater attention to the incarnational and institutional aspects of Catholicism. His focus became Christological rather than primarily Pneumatological, but he retained the theme of a synthesis of contrasting elements.
It is significant that Tillich, who particularly insisted on the ‘Protestant principle’, had difficulty in accepting the doctrine of the Incarnation. Although he was quite prepared to acknowledge the symbolic value of the biblical picture of Jesus as the Christ, he seemed unable, consistently with his own principles, to admit a real union of the divine with the human in Jesus Christ. George Tavard rightly observes of Tillich: ‘When he himself tried “to find new forms in which the Christological substance of the past can be expressed,” the Christological substance vanished’