"Oppression is the act of using power to empower and/or privilege a group at the expense of disempowering, marginalizing, silencing, and subordinating another group. Oppression does not need established organizational support; it can be rendered on a much smaller individual scale. It is particularly closely associated with nationalism and derived social systems, wherein identity is built by antagonism to the other. The term itself derives from the idea of being "weighted down." -- http://en.wikipedia.org/wiki/Oppression
My Facebook account was shut down yesterday, effectively oppressing my ability to communicate with non-atheists. Did you experience similar situations on other message boards?