The reign of Uzziah was drawing to a close, and Jotham was already bearing many of the burdens of state, when Isaiah, of the royal line, was called, while yet a young man, to the prophetic mission. The times in which Isaiah was to labor were fraught with peculiar peril to the people of God. The prophet was to witness the invasion of Judah by the combined armies of northern Israel and of Syria; he was to behold the Assyrian hosts encamped before the chief cities of the kingdom. During his lifetime, Samaria was to fall, and the ten tribes of Israel were to be scattered among the nations. Judah was again and again to be invaded by the Assyrian armies, and Jerusalem was to suffer a siege that would have resulted in her downfall had not God miraculously interposed. Already grave perils were threatening the peace of the southern kingdom. The divine protection was being removed, and the Assyrian forces were about to overspread the land of Judah.

Esajas, som var af kongelig slægt, blev kaldet til at være profet, mens han endnu var ganske ung. Det skete ved slutningen af Uzzijas regeringstid, da Jotam allerede havde overtaget mange af kongens officielle pligter. Esajas gerning faldt i en tid, som var særlig farefuld for Guds folk. Profeten oplevede Israels og Syriens forenede hæres indfald i Juda. Han så assyrerhæren slå lejr foran rigets store byer. I hans levetid ville Samaria falde, og Israels ti stammer ville gang på gang blive angrebet af de assyriske hære, og Jerusalem ville opleve en belejring, som ville have ført til byens fald, hvis ikke Gud havde grebet mirakuløst ind. Sydrigets fred var allerede alvorligt truet. Gud var ved at tage sin beskyttelse bort, og de assyriske hære stod i begreb med at oversvømme Judas land.