Isaiah lived 700 years before Christ’s coming and used to deal with the issue of the emergence of a “Savior” more than other prophets. In his words, the best instance to save the Israelites was a person named “Immanuel”. (Immanuel, literally, means God is with us)
Prior to Isaiah the concept of Messiah and the Savior did not have a universal perspective. But after him “the Concept of Messiah” remained active and Messiah has acquired a global function.
The prophets after him also promised a better future and the advent of a Messiah and an immortal religious government until the light of prophethood reached Daniel (PBUH)…
Isaiah, chapter 7, verse 14