Vision related roughly beforehand in religious language (6)
I believe the answer is:
coptic
'religious language' is the definition.
(I've seen this before)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for coptic that I've seen before include "Egyptian Christian church" , "Egyptians in the past" , "Egyptian church language" , "Sweet; fungus" , "Ancient Christian church of Egypt" .)