Activism, in a general sense, can be described as involvement in action to bring about change, be it social, political, environmental, or other change. This action is in support of or opposition to one side of a controversial argument.
There are many different forms of activism; a select list follows.
... Church (USA) has split a number of times in its history. Many of these historic splits have been resolved. From the continuing branch churches, some have split in turn. ...