What role did religion play in a knights life?

The Catholic church set the tone for everyone in the society. Knights were given a code of conduct to pledge to a priest. This was needed because in the early middle ages knights were a little more than "wise guys" and were killing, raping, and looting villages and people, so the church stepped in and wrote a code of conduct for the knight. They had to promise to protect women and children and if they didn't follow the code they would be excommunicated.