The Ascension of Isaiah, sometimes referred to as the Assumption of Isaiah, is one of the pseudepigrapha: a group of texts written under false names associated with biblical characters. The text is also referred to as the Martyrdom of Isaiah, the Testament of Hezekiah, or the Vision of Isaiah. Those names are also associated with the three main sections of the text, and some scholars think each was originally a distinct work and that the three were later combined under a single title. As with other non-biblical texts, the Ascension of Isaiah contains various flaws that prevented it from being accepted as Scripture by the early church. Unlike other such texts, historians believe the Ascension of Isaiah may have been promoted and understood as fiction from its first writing.
The first portion of the Ascension of Isaiah describes Isaiah’s predictions to Hezekiah that the next king, Manasseh, will be evil and ungodly. Manasseh demands that Isaiah retract those prophecies, so Isaiah flees to the wilderness. He is eventually captured. Isaiah is then executed, with the cooperation of a demon-inspired false prophet, by being sawn in half. This corresponds to various Jewish traditions and might also be alluded to in Hebrews 11:37.
Though recognized as an individual segment, the Ascension of Isaiah’s second main division is found in the middle of the martyrdom narrative. This portion is sometimes called the Testament of Hezekiah. The text supposedly prophesies the coming of Christ, widespread evil in the world and even in the church, and events related to the end times.
The third part of the Ascension of Isaiah is the most infamous, and it’s the reason the text is generally referred to using the term ascension. Isaiah is led on a supernatural tour of each of the seven ascending heavens, guided by an angel. During this vision, Isaiah appears to be in a coma: his body is alive, but inert, and only his mind is on tour. Isaiah’s visions depict a triune God and many splendors in heaven. Isaiah then descends through each heaven, this time watching Jesus as He makes His way toward earth and the virgin birth. According to this part of the text, Satan conspired to have Isaiah sawn in half because he had seen these visions.
Some aspects of the Ascension of Isaiah correspond to biblical ideas. Others, such as its concept of Jesus, lean toward Arianism or other heretical views. The text itself is believed to have been written in separate sections between the first and third centuries. It’s possible that some sections, such as the account of Isaiah’s martyrdom, were first written by Jewish teachers and later edited by Christians. Due to the late writing date and theological content, no part of the Ascension of Isaiah was accepted as inspired Scripture by the early church.
As with other pseudepigrapha, the Ascension of Isaiah is an interesting reference point for legends about biblical characters. It is not, however, a work comparable to actual inspired Scripture.