In 1800 Hegel published Fragment of a System. Here Hegel struggles with the problem of overcoming oppositions especially between the finite and infinite. As spectators, life appears as nature given to our understanding, but nature is transitory and therefore thought thinks nature in terms of unity with the infinite. This creative unity of nature and the infinite is not a conceptual abstraction but is God (and must also be defined as Spirit since it is neither an external link between finite things, nor a purely abstract concept or abstract universal). Rather infinite life unites all finite things from within, however without annihilating them. Infinite life or Spirit is a living unity of the manifold.
Hegel use of the word ‘Spirit’ (German: "Geist") is important to the development of his philosophy. The question is whether we can conceptually unify the finite and infinite without dissolving either. Hegel in Fragment of a system maintains that is not possible. The gulf between the finite and infinite inevitably tends to merge and so reduce one to the other while, if it affirms their unity, it inevitable tends to deny their distinction. We can see the necessity for a synthesis in which the unity does not exclude its distinctions – but the question is whether we can think that? Unifying the One and the Many within the One without dissolving the Many can be achieved only in living, and not in thinking….this is religion. In this sense philosophy is subordinate to religion. Philosophy can show us what is required but it cannot think it. Here Hegel turns to the Christian religion – because the Jews objectified God as being above and outside the finite (which Hegel calls “bad infinity”) but Christ discovered infinite life within himself – hence the unity can only be lived as Christ lived in a life of love.
For Hegel, Overcoming the finite and infinite without losing either is love, not thought. Yet it is the task of philosophy to try to think what religion lives and to accomplish this philosophy must avail itself of a new logic – one that is able to follow the course of life and does not leave opposed concepts in irremediable opposition. This new logic marks Hegel’s transition from theologian to philosopher.
Summaries of Hegel's works and ideas (best read in succession):
Hegel - Fragments of a SystemHegel On Self-Consciousness