In Moltmann’s first major work, Theology of Hope, an inspection of the footnotes reveals the philosophical and theological lineage from which Moltmann comes; there is a moderate amount of reference to Buber, Gadamer, and Heidegger, but plenty of interaction with, and criticism of, Bultmann. Though one needs to keep in mind that Moltmann doesn’t always explicitly reference the thinkers who have had an impact on his thinking; Hegel, for one, while not really being a noticeable interlocutor in Moltmann’s writings, certainly is a philosopher whose shadow is cast wide over Moltmann’s thought, being obvious in how his theology revolves around the cross-resurrection dialectic. There is also Luther whose theologia crucis is likewise found in Moltmann’s accent on the ‘crucified god’ and the notion that when God is revealed, it is through the suffering God on the cross. (For a discussion of Moltmann’s utilization of Luther’s theologia crucis, see Burnell Eckardt, Jr., ‘Luther and Moltmann: The Theology of the Cross’, Concordia Theological Quarterly 49.1, 1985: 19-28). In addition to all this, Moltmann should be read with the entirety of German continental philosophical thought (e.g. Bloch) as a backdrop, along with the reformed and liberal Christian theologies of his time represented by the likes of Bonhoeffer and Barth, the latter being frequently cited by Moltmann and explicitly acknowledged for his fundamental influence (Experiences in Theology, 6; Fortress, 2000). Elsewhere, Moltmann states that “after Karl Barth’s monumental Dogmatics, I thought there could be no more theology” (How I Have Changed, 15; SCM, 1997).
A conspicuous aspect of Moltmann’s hermeneutic is his heavy use of Jewish philosophers and theologians, such as Bloch, Freud, Maimonides, Rosenzweig, and Heschel. He even draws upon the Jewish Kabbalistic tradition which is seen in his adoption of the creation idea of zimzum (see e.g. God in Creation, 86-87; Fortress, 1993). One Jewish philosopher whom Moltmann is quite indebted to is the neo-Marxist philosopher Ernst Bloch, whose work Das Prinzip Hoffnung (The Principle of Hope) was essentially an ur-source for Moltmann’s Theology of Hope. In fact, in 1964 Barth posed the following question to Moltmann: “Is your Theology of Hope anything but Mr. Bloch’s ‘principle’ of hope baptized?” (see Müller-Fahrenholz, The Kingdom and the Power: The Theology of Jürgen Moltmann, 42; Fortress, 2000). Also, for a deeper study on the relationship between Bloch’s Das Prinzip Hoffnung and Moltmann’s Theologie der Hoffnung, see Gerald O’Collins, ‘The Principle and Theology of Hope’ (Scottish Journal of Theology 21.2, 1968: 129-144).
Moltmann’s heavy reliance upon Jewish resources is unique amongst Christian theologians, not seen since the time of Aquinas and his use of Maimonides, and is most likely due to guilt over the atrocities committed against the Jewish people by Nazi Germany. Nevertheless, Moltmann’s extensive interaction with Jewish works is a desirable enrichment of his own theological project, giving him a distinct leverage on the rest of the Reformed theological tradition.