An historical compendium of Christian theology in the second millennium, filled with its richness, its struggles, and its splintering into diverse orthodoxies which today are committed to a dialogue leading to reconciliation. Monastic theology, meditation on Scripture, the celebration of the Christian mysteries, moral ascent, mystical experience, expectation of the final coming, are all seen as so many stops along the road to the heavenly Jerusalem. The mendicant orders set out to renew the original spirit of evangelization. They accept the challenge of secular science and construct the scholastic systems. They inflict painful damage upon a continually troubled Christianity which is in need of reform and a return to the Scriptures. The sluggish reaction of Trent reflects the secular character of Roman Catholicism and its opposition to the rebellion of the church to the north. But, for many, only reason and history can be relied upon to assess the inheritance from the past, while the Gospel itself passes judgement on those who are Christian in name only. Revolutionary changes in economics, law, and culture; totalitarian ideologies; and world conflicts put the Christian traditions to the test. The second Vatican Council opens the road to renewal and ecumenical reform. The moral freedom and material well-being of the early Christians stands in contrast to the widespread spiritual malaise and misery of a great part of today's world. In today's phenomenal world of technology for the masses, Christianity, together with other religions, seeks the way to the human heart filled, as always, with contradictions. Among the protagonists appearing in this long historical pageant are Anslem, Bernard, Hugo, Abelard, Joachim, Francis, Bonaventure, Thomas, Duns Scotus, Dante, Ockham, Catherine of Siena, Valla, Nicholas of Cusa, Ficino, Savonarola, Erasmus, Luther, Zwingli, Calvin, Theresa of Avila, John of the Cross, Suarez, Bellarmine, Carnelius a Lapide, Spener, Schleiermacher, Rosmini, Manzoni, Leo XIII, Harnack, Troeltsch, Bultmann, Barth, Bonhoeffer, John XXIII, and the most recent spokesmen for Christian ecumenism.