Respect is the cornerstone of a good environment. You create a respectful community by requiring that everyone treat everyone else with the respect that they deserve. You do this by having written policies and by actively enforcing those policies. Don’t let people get away with disrespectful comments. All members of your community (regular members and staff members) must treat one another with respect at all times.
You should encourage your members to attack the point and not the person. Address what people say, don’t try to attack them as human beings for having a given view. This extends to respect of choice.
[Managing Online Forums by Patrick O’Keefe pages 219-220]