vjack over at Atheist Revolution wrote an excellent challenge that we should all heed: Be an Atheist Activist in 30 Minutes a Week. If you care about the world you live in, I hope you'll read it and take it to heart.
But, I would add my own suggestion to his: Focus on children.
This is one of the best "tricks" that The Religion Virus has evolved in its arsenal of memes. In virtually every major religion in the world, religious training starts almost in infancy, as soon as a child learns to speak. Most religions advocate immersion of the child in a religious culture, such that religion permeates school, home, work, and even play.
And with good reason: Religions that have evolved this teach-our-children-young idea are immensely more successful than those that don't. Children's minds are highly evolved to soak up information, to take in all the lessons possible from their parents, because human survival relies on our incredible ability to pass vast amounts of information to our children via language. If a religion misses the opportunity of youth, it usually will miss completely.
This is borne out by the facts: Most children follow the religion of their parents, or one very closely related to it. It is rare for, say, a Jew to become a Baptist, or a Muslim to become a Hindu. If religion were truly a rational, logical choice that people made, based on an objective analysis of each religion's teachings, then one would expect that Christians would have Muslim children, Jews would have Baptist children, and Atheists would have Hindu children. But this rarely happens. Teaching religion to children is one of the most important memes in the arsenal of every major religion.
We Atheists need to adopt this same meme. Over and over, I see bloggers and authors (including me!) aiming their blogs and books at adults. But adults rarely change their beliefs, even in the face of overwhelming evidence that their religion is without factual foundation and full of contradictions. When we argue with them, we're mostly wasting our time.
It's the children that are important. "Give me the boy, and I'll give you the man," is the famous quote by St. Ignatius, way back in the sixteenth century, and is more true today than when he said it.
Religions know this, apparently far better than atheists. What is the biggest battle they're fighting in America today? To keep secular teaching away from their children (and yours). Religious parents of all faiths know all too well that if their children are exposed to modern science, accurate history lessons, psychology and sociology, the child is far more likely to become a deist, agnostic or atheist.
Atheist activists need to adopt this same meme. Children must be shown, beginning as early as possible, that the world is not a mysterious, magical place full of angels and demons, with a voyeuristic god that watches your every move, but rather is a wonderful result of physical processes that are well understood. Children need to be taught the beauty of physics, the "magic" of chemistry, the vastness of the universe, and the wonderful insights of psychology and sociology.
Children also need to learn about natural ethics. They need to know there is a real philosophical foundation for humanist morals, rather than some god who merely dictates obsolete, contradictory and even horrifying laws that we're expected to obey without question.
So, take vjack's advice: Become an activist for thirty minutes a day. But focus your efforts on our children, where the future lies. Redouble your efforts to fight the teaching of creationism in school. Write letters to your newspaper in support of a modern science curriculum. When you talk to your children's friends, don't be afraid to tell them you're an atheist, in a frank and matter-of-fact manner, and be ready to answer their questions.