Transtheistic is a term coined by philosopher Paul Tillich or Indologist Heinrich Zimmer, referring to a system of thought or religious philosophy which is neither theistic, nor atheistic, but is beyond them.
Zimmer applies the term to the theological system of Jainism, which is theistic in the limited sense that the gods exist, but become immaterial as they are transcended by moksha (that is, a system which is not non-theistic, but in which the gods are not the highest spiritual instance). Zimmer (1953, p. 182) uses the term to describe the position of the Tirthankaras having passed "beyond the godly governors of the natural order".
The term has more recently also been applied to Buddhism, Advaita Vedanta and the Bhakti movement.
Nathan Katz in Buddhist and Western Philosophy (1981, p. 446) points out that the term "transpolytheistic" would be more accurate, since it entails that the polytheistic gods are not denied or rejected even after the development of a notion of the Absolute that transcends them, but criticizes the classification as characterizing the mainstream by the periphery: "like categorizing Roman Catholicism as a good example of non-Nestorianism". The term is indeed informed by the fact that the corresponding development in the West, the development of monotheism, did not "transcend" polytheism, but abolish it, while in the mainstream of the Indian religions, the notion of "gods" (deva) was never elevated to the status of Brahman, but adopted roles comparable to Western angels. "Transtheism", according to the criticism of Katz, is then an artifact of comparative religion.
Paul Tillich uses transtheistic in The Courage to Be (1952), as an aspect of Stoicism. Tillich stated that Stoicism and Neo-Stoicism
are the way in which some of the noblest figures in later antiquity and their followers in modern times have answered the problem of existence and conquered the anxieties of fate and death. Stoicism in this sense is a basic religious attitude, whether it appears in theistic, atheistic, or transtheistic forms.
Like Zimmer trying to express a religious notion that is neither theistic nor atheistic. However, the theism that is being transcended in Stoicism according to Tillich is not polytheism as in Jainism, but monotheism, pursuing an ideal of human courage which has emancipated itself from God.
The courage to take meaninglessness into itself presupposes a relation to the ground of being which we have called "absolute faith." It is without a special content, yet it is not without content. The content of absolute faith is the "god above God." Absolute faith and its consequence, the courage that takes the radical doubt, the doubt about God, into itself, transcends the theistic idea of God.
Martin Buber criticized Tillich's "transtheistic position" as a reduction of God to the impersonal "necessary being" of Thomas Aquinas.