Richard Scroop, the Archbishop of York, leads the rebellion against the king in Henry IV Part 2. The Archbishop uses his religious authority to his advantage. He attracts a sizable following because it seems to many that God is on his side.
When Prince John meets with York at Gaultree Forest, he accuses the Archbishop of abusing his position in the church: "You have ta'en up, / Under the counterfeited zeal of God, the subjects of his substitute, my father, / And both against the peace of heaven and him / Have here up-swarm'd them" (4.2.1). In other words, Prince John reminds York that the king is God's "substitute" on earth, which is a reference to a political theory know as the doctrine of "divine right." According to this political theory, kings are appointed by God to be earthly representatives and, therefore, subjects should never challenge the monarch's authority. In fact, rebelling against the king was considered a sin against God in addition to being treasonous. (You can read more about this by going to "Quotes" for "Power.")