Jürgen Moltmann visited the United States following the infamous success of his infamous book Theology of Hope. He traveled throughout the U.S.A. and these lectures were compiled and published in Moltmann's book: Religion, Revolution and the Future (RRF). RFF discuses Marxism, Society and Hope. Douglas Meeks' translation of this book contains a helpful introduction:
From September, 1967, to April, 1968, Jürgen Moltmann, Professor of Theology at Tübingen University in Germany, sojourned in the United States. While he was pivotally located as Visiting Professor of Systematic Theology at Duke University, he traveled widely to almost every major region of the nation and visited many of the large academic and urban centers. This book is compromised of a portion of the lectures and essays with which Professor Moltmann introduced himself and his thought to the American continent.
Moltmann, Jürgen Religion, Revolution and the Future. New York: Charles Scribner's Sons, 1969. Trans. M. Douglas Meeks. N. pag. Print.
I've chosen a selection from Religion, Revolution and the Future in the section 'The Abundant Man' to demonstrate the excellence of this book, and in particular in Moltmann's charge even today for the Church and Christians in liberating the captives because no one is free in the land of the free, until all are free:
The promised future of God's reign is directed not only to man's internal happiness, but toward that full humanity which is denied by poverty, hunger, illness, and suffering. Through industrialization it is now more possible than ever to achieve success in the struggle against hunger. Therefore, Christianity should participate in those social programs which strive for conditions in which hunger and poverty and illness cease for as many people as possible. In such participation, there are, in particular, two viewpoints that it can develop.
First, with respect to the distribution of the social product and the politics of capital investment, Christianity can become the advocate of those groups that have insufficient or no public representation in a particular society. It can further urge concern for a balance between consumption and capital investment. A society which limits itself to investing, sacrifices the present to the future. But a society which avoids the category "future" forfeits the power for farsighted investment. It sacrifices the future for the enjoyment of the present.
Second, it can become the advocate of those groups of hungry and destitute men who live outside the industrially developed society. For no man will be abundant unless all are abundant; no man will be satisfied if some lack satisfaction; no man will be happy until all are happy. The struggle against hunger and poverty through the forces of industrialization must be either universal and without distinction or it has not even begun.
Moltmann, Jürgen Religion, Revolution and the Future. New York: Charles Scribner's Sons, 1969. Trans. M. Douglas Meeks. 122-3. Print.
Related: Abundant Man, Jürgen Moltmann, Marxism, Religion Revolution and the Future