According to the liner notes to the album Refrain of Evangelion , director Hideaki Anno had originally wanted to use a piece of classical music as the opening, [b] but due to concern that this might confuse the anime viewership, a decision was made to use a more upbeat J-pop song instead. She had been given specific instructions by the producer to make the wording sophisticated and "philosophical". She reveals she got inspiration for the title from the manga A Cruel God Reigns. The original song included a male chorus, which was cut at director Hideaki Anno's request in order to "emphasize maternal affection". Both are considerably different in feel from the more hard driving original.
NEON GENESIS EVANGELION - A CRUEL ANGELS THESIS OFFICIAL by Misc Cartoons @ infogramma.info
It is used as the opening to the series, and two instrumental versions of it are played in the finale episode, " Take care of yourself. A similar version can also be heard during the intermission between the two parts of Evangelion: Death and Rebirth. The single was released on October 25, with the part number KIDA and it also reached a peak rank 17 in the Oricon album database, appearing in the ranks 61 times. Unlike it is commonly assumed, this song was written without any involvement from the show's creators.
The lyrics are by Neko Oikawa while the arrangement is by Toshiyuki O'mori. This song was written with relatively limited involvement from Hideaki Anno and the production staff, being handled by producer Toshimichi Otsuki. Oikawa apparently had very little knowledge of the show, which was under production at the time with the episodes not having been colored. According to tweets and interviews, Oikawa went through a proposal of the show possibly Neon Genesis Evangelion Proposal and watched two unfinished episodes on fast-forward, only serving to broadly "fit" the anime after the fact   .
New Feature! In kanji view, mouseover a kanji character for lookup information! Lyrics from Animelyrics. Unfortunately, I can't tell what they're singing there's too much overlap. I think the last thing they sing could be " ai ga fusei ," which can be roughly translated into "Love is a sin wrongdoing.