Are you just a person who thinks that everyone be they, male, female, gay, straight, black, white, trans, or are the same gender as the sex they were born with should be equal under the law and receive the same treatment?
Then you can join the group.
It is that simple.

This is not a movement.
There is not a mission statement.
There isn't a common rhetoric used by the members of this group.
Looking at the members of this group will tell you absolutely nothing about them beyond that they agree that people should be equal, and even that isn't the same person to person. Everything else about them could very well be completely different.
Everything done and everything said is done by individuals and nothing is to be done in the name of this group.
Members can, and are encouraged to, argue and disagree amongst themselves about what exactly equality entails and what would need to be done, if anything, to achieve equality.

The rules: The rules.
Direct all questions here: Questions thread.
Direct all ideas for improvement to the group here: Idea thread.

The reason I worded the title like that is because I don't take the label brony for myself.