At the time that Measure for Measure was written, England was a Protestant country, meaning that the monarch at the time, James I was the head of the Church of England. However, the England that Shakespeare was brought up in was still living with the remnants of a Catholic history, and so the religious beliefs that he would have learnt about as a child would have been those of the Catholic faith. Although Shakespeare was writing the play for a Protestant audience and a Protestant king, he was setting the play in a Catholic country, so this gave him an opportunity to feature his religious beliefs as a Catholic in the play.
One of the characters in the play particularly affected by religion is the Duke, as he discards his secular identity and is able to take.....