Terrorism isn't religion-based. Please read up on facts.
But to make it easy for you, here's a rough idea:
Terrorism: def; the use of fear through violence and propaganda (threats) to influence a decision (primarily political)
Terrorism has been used throughout history because of one reason: It Works.
And people mainly use it, not because of difference of religion, but feelings of oppression. Famous Quote: "One man's terrorist is another man's freedom fighter." -Gerald Seymour
You most likely made the reference because you think that all terrorists are Muslim and hate Christians. Wrong. They feel they are being oppressed and abused by America, and in all fairness they have the right to believe that, because we do a lot of what we are accused of.
There, crash course in terrorism.