Help!

I am getting married in an 16thC priory in Dec in a Civil Ceremony and I am really keen to have some gregorian chant/choral music with a church like flavour playing - however - because it is civil it HAS to be non religious - I have found the Prophetiae Sibyllarum by Orlandus Lassus and this would be perfect but dependent on which site I visit depends on whether I am told it is religious or secular - my main understanding is that it is visiting a number of sybelic prophesies which are non religious (unless we revert to the Gods of Greece/Rome) - can anyone point me to a translation of the lyrics (ideal as we would need to prove it is secular) and/or alternative music that might be suitable? thanks