While I generally dislike the posture of rigidified hostility to any group, I am a lifelong anti Catholic. Any social setting which is authoritarian and anti-democratic is repugnant to me excepting military and emergency service activities. Positive atheism, I feel, will want to find more rational substitutes for that. We need our atheist radio stations, our atheist out-reach people on college campuses, our weekly column in the paper. We need to reach out to those who need us, and must do so in a visible, and highly positive, manner.
Organized atheism exists only to counter the claims of theism.
Anything more than this belongs in another category, and is not rightly called atheism. One's atheism can influence one's activism in certain subjects. For example, in my home state of Oregon, we passed a wonderful Death With Dignity Act. This Act has powerful protections against abuse, and is even covered by the Oregon Health Plan. The bulk of the funding for the opposition came directly from the Vatican, and the rest from other religions interests.