Fanatic.

Is there a difference between a religious fanatic and a Jesus fanatic? A fanatic is a a person with devoted and uncritical enthusiasm or zeal. They have strict standards and little tolerance for contrary ideas or opinions.

Therefore, a religious fanatic is hard to be swayed from the teachings of their religious persuasion.

A Jesus fanatic is one who believes in the teaching and work of Christ, and is not swayed by religious inference. The two are not one and the same!