Context: The Orthodox nobles' rights were nominally equal to those enjoyed by Polish and Lithuanian nobility, but there was a cultural pressure to convert to Catholicism, that was greatly eased in 1596 by the Union of Brest. See for example careers of Senator Adam Kisiel and Jerzy Franciszek Kulczycki.

Question: What other rights were equal to orthodox nobles?
Answer: Polish and Lithuanian nobility

Question: What social pressure was pressing down the people?
Answer: convert to Catholicism

Question: What greatly eased the cultural pressure towards Catholicism. 
Answer: Union of Brest

Question: What year was the union of brest
Answer: 1596