I recently read a news article about a Swedish Leftist who several years ago voiced his support for Pol Pot, who was the prime minister of Cambodia from 1975-1979. Apparently when he voiced his support for Pol Pot he was unaware of the atrocities being committed by the Khmer Rouge regime at the time. Now years later he expressed his regret for ever giving his support for such a man and such an organization. As this man said "I was at that time a member of a friendship association which was a remnant of the anti-Vietnam/Cambodia War movement in Sweden, which was very strong in the Western world....Of course we didn't want to believe that the liberators had become oppressors." In other words he gave his support for the government and the dictator because he viewed them as supporting the same ideals and type of government that he supported.
When the Khmer Rouge came to power in Cambodia and over threw the "oppressive" government and "liberated" the people, this man and others voiced their approval of what was done, but it was only later they found out what was actually happening and who they were really supporting. So the lesson to be learned from this to think about who you really support.
My sister once told me about an experience she had when she was working on her PhD at the University of Wisconsin-Madison. She told me about how some people she knew approached her as asked if she would like to support an international environmental group through a donation or by getting a subscription to their magazine. She looked over their literature and magazine to get a sense of the organization and when she did this she found that the organization supported and actively endorsed and worked for several things that she very much did not agree with. She said that even though their selling point was protecting the environment, which can be a noble and worthwhile endeavor, their methods and ultimate purpose were questionable, or down right immoral.
Many times there is a movement or ideology that many different groups of people will join and participate in but some of those supporting it are doing it for not so honorable reasons. One movement that has been gaining some news coverage lately is the opposition to Proposition 8 in California, even after it was passed. While some people who oppose Prop 8 may have legitimate concerns, others view it as an opportunity to attack a specific religion or religion in general. They are in effect using it as an excuse to oppress and attempt to disenfranchise those who have religious beliefs. So there may be some who think there cause is honorable and good, but they do not want to believe that "liberators" are about to become oppressors.