Great Being is the term used by sociologist August Comte to refer, in a confused and decidedly Christian sort of way, to a collective level of being, independent of individual humans, and capable of directing human action towards altruism, unity, and peace.
I already understand that the Great Being, in your conception, is, by its very nature, the expression of the whole order of things—not merely of the order of man, but of the external world (Comte, 2009: 74)
Note, Comte did not believe in a disincarnate Consciousness. He used the term Great Being and Supreme Being to reference the "subjective" immortality of humans, made possible, essentially, by human memory and tradition.
We find, then, that the social existence of man [sic] really consists much more in the continuous succession of generations than in the solidarity of the existing generation. The living are always, by the necessity of the case—and the more so the more we advance in time—under the government of the dead. Such is the fundamental law of human order.
To enable us to grasp it more fully, let us distinguish the two forms of existence which are the portion of each true servant of Humanity. The one is but for a time, but it is conscious. This constitutes the life of man, properly so called. The other, with no direct consciousness on the part of man, is yet permanent, and does not begin till after death. The first involves the presence of the body, and may be termed objective, to mark more clearly its contrast with the second. That second leaves each one to exist only in the heart and intellect of other and deserves the name of subjective. This is the noble immortality, necessarily disconnected with the body, which Positivism allows the human soul. It preserves this valuable term soul—to stand for the whole of our intellectual and moral functions, without involving any allusion to some supposed entity answering to the name (Comte, 2009: 73-74, emphasis added).
Comte felt that the "subjective" body of humanity is where human behaviour is regulated. Comte felt that this subjectivity, this "Great Being" was still evolving: "The Great Being is not yet fully formed; yet no jar of its component parts was ever able to keep out of sight its gradual progress towards formation" (Comte, 2009: 78). Comte also felt that the evolution of the Great Being was humanity's "final object." After it was completely evolved, humanity would enter into a period of altruism, peace and unity.