Agent Garbo: The Brilliant, Eccentric Secret Agency Who Tricked Hitler and Saved D-Day by Stephan Talty

Double Cross: The True Story of the D-Day Spies by Ben MacIntyrre

Spies in the Vatican: The Soviet Union's Cold War Against the Catholic Church by John Koehler

The other end of the telescope from the Mossad book.  Here clerical spies recruited by Soviet block nations infiltrate the Vatican, especially during the papacy of John Paul II and his advocacy for Polish Solidarity.  This ends up being a contrast in religions not necessarily in espionage, as the Catholics evidence not knowledge of the presence of agents in the clerical ranks whereas Mossad is a penultimate enforcer as well as expert spy.