A real quick note: it is thematically important that Alvard is dying of cancer when he is frozen - cancer is a kind of unlimited cell growth where a cell line does not stop replicating when it should - a very literal attempt at unfettered life and immortality which kills the larger organism. The immortality of the individuals in society has also killed its host, humanity as a whole.
Also, when Alvard's Bible asks "Who is the Son of Man?" the dominant Christian zeitgeist and the prophecy of Daniel and the Ancient of Days
would have us believe this refers only to Christ, but in reality it is a term which in its original Jewish sense was meant to differentiate that which was mortal and in need of repentence from that which was divine or angelic, immortal and timeless. Here, the children of men have put aside that mortality in theory, but they are still dead and dying - they just don't know it. Christ's use of the term came to represent a Being both fully human and fully divine, who would even be subject to the temptations of the flesh and the threat of death and suffering.