No, that's just an excuse. Certain people are bored, or need to distract their nobility with an external focus. So, classic maneuver: start a war. Most of the realm nobility follow along.
Certain other people are angry that their individual agenda was not adopted. Or that they didn't get the power/position they feel they deserved.
And some people just have a persecution complex, and lash out mindlessly. 
And they were handed the best of reasons by the Church. There were plenty of other wars brewing elsewhere with several of the participants. The church blundering about doing what it pleased with no thought of the consequences has brought this about.
