The use of Latin would do great damage to the European dream of unity. There's already a great distance between those who (are suppose to) represent the European population and the European citizens themselves. If they started using their own language it'd be like the old days where one could only come close to god via the church because the bible was written in Latin, a language only the men of the church understood…
The bible wasn't originally written in Latin. The Old Testament is mostly written in Classical Hebrew (source: http://en.wikipedia.org/wiki/Hebrew#Classical_Hebrew ), except for large sections of the books of Daniel and Esra - these are written in Aramaic (source: http://en.wikipedia.org/wiki/Aramaic ) The New Testament is originally written in Koine Greek (source: http://en.wikipedia.org/wiki/Novum_Testamentum_Graec…
Its also relevant because of lack of control and a rather concrete expression of rebellion. "We forbid you to do this" "Been there done that". Rabble rousing always happens and never amounted to much; publishing an illegal book was a substantial escalation.