Sadly Sings Destiny Lyrics

Lyric discussion by Atone 

Cover art for Sadly Sings Destiny lyrics by Blind Guardian

I think it's pretty clear that this is about the idea that Judas didn't have a choice in betraying Christ. The betrayal needed to happen to complete the ransom / fulfill prophecy. Christ told Judas in advance that Judas would be the one to betray him. And when it came time for the betrayal, it says that Judas was possessed by Satan. Rather than being the greatest sinner in history, by this view he was a tool, a necessary evil in a scheme much bigger than himself.

It seems clear that this song is Judas being haunted by visions/voices/demons/god pushing him towards his unavoidable destiny.