1. Charles I was thought to be acting too nice to the catholics in England.
2. Parliment wanted more power.
3.Some people wanted to have a new king as Charles I was too reliant on the divine rights of kings. People were jealous about how special the king seemed.
The outcome: Charles I got executed and parliment won and for a while, Oliver Cromwell ruled (not as king, though). They then had a new king, Charles II.