If you know more than Jon Snow, you’ll know that religion in Westeros bears striking similarities to faith in the real world.
Game of Thrones author George R.R. Martin has made it clear that the complex belief systems in his renowned series are rooted in reality.
There are the Old Gods of the Forest, whose followers in the North find their faith in nature -- in rocks, streams and in the faces of ancient weirwoods. Like the pagan traditions of Western Europe, this earth-based spirituality was later supplanted by the monotheistic Faith of the Seven, in which a hierarchy of priests leads followers in worshiping just one God in seven different forms. Martin has said the Faith of the Seven is based loosely on the Christian belief in the Trinity.
The latest faith group to storm Season Five of HBO’s adaptation of the novels is the Faith Militant, or the Sparrows. This King’s Landing cult is obsessed with purifying the Faith. They violently punish sin and are trying to root out brothels, taverns and all those who sell idols from other religions.
In an interview with Entertainment Weekly, Martin said the rise of this King’s Landing cult is meant to resemble the religious revivals that rocked the medieval Catholic Church.
Queen Cersei may have tried to use the Sparrows as pawns to secure her claim to the throne. But in fact, she's the one being played by forces way beyond her control.
If you look at the history of the church in the Middle Ages, you had periods where you had very worldly and corrupt popes and bishops. People who were not spiritual, but were politicians. They were playing their own version of the game of thrones. ... But you also had periods of religious revival or reform -- the greatest of them being the Protestant Reformation, which led to the splitting of the church -- where there were two or three rival popes each denouncing the other as legitimate. That’s what you’re seeing here in Westeros. ... So now [Cersei] has to deal with a militant and aggressive Protestant Reformation, if you will, that’s determined to resurrect a faith that was destroyed centuries ago by the Targaryens.