A great amount of ink, both real and digital, has been expended in an attempt to nail down exactly what Humanism is, and isn't. I'm not going to pretend here that I have the definitive definition. Instead, I'm going to give a pragmatic, actionable definition of Humanism that works well for me and what I do as a Humanist activist.
Humanism is a lifestance or philosophy that prioritizes social, economic and ecological justice, human rights, rationality and secularism. It's main values are reason, compassion, optimism and action.
Note that this definition does not include atheism. I don't believe that disbelief in God is necessary to Humanism, but I do think that prioritizing people over God is. Even if one believes in some kind of nebulous, distant and unknowable creator, it is possible to be a Humanist.
A commitment to social, economic and ecological justice is a must. In addition, because Humanists also value science and reason, it is probably impossible to be both a Libertarian and a Humanist. Libertarian economic theory is pseudoscience at best, and at its worst it bears more than a passing resemblance to religious dualism. Libertarianism needs to join astrology and phrenology in the dustbin of history.
Now, reasonable people can disagree with my definition, and perhaps it could be expanded to more carefully delineate and explain my beliefs, but my definition works as an "elevator speech." It's quick and clear and ripe with threads for further discussion.
I don't see this definition as my final thoughts on this issue, (barring my sudden death after posting this.) Instead, I see this definition as the best approximation of my thoughts on the subject now. As I continue to devote my time to various causes in Providence, in Rhode Island, in the United States and in the world, this definition of Humanism will allow me to frame my actions and shape my thoughts.
And if my definition changes over time, I'm sure I'll note that in a blog somewhere.