What does it mean to be a Pagan?
The etymology I like best for "pagan" is that it comes from Latin pagus, " local district, especially as seen as inhabited by a particular tribe." Yes, I know that arguing from etymology is absurd (did you know that if you argue from etymology you can prove that "black" is "white," since "black" comes from a Proto-Indo-European root meaning "shining?"), but this makes for a good definition of Paganism: it is the religion appropriate to the natural and social environment of the worshiper. Many Pagans see Paganism as being "earth-based." I don't; to take just one example, in what way was the religion of the apartment dweller in ancient Rome "earth-based?" Yet few would argue that it wasn't Paganism.
If we use the pagus etymology, Paganism becomes the religion appropriate to 1) the physical environment, and 2) the cultural environment, of the worshiper. The first handles in part the "earth-based" part of most people's definitions. It also, however, would include the structures of cities. In this sense a Pagan would have to answer the question, "how do I fit my religion into the place where I find myself?"
Note two things about this. First, it means that if a person moves to a different place their religion would change in some way, as it aligns itself to the new place. Second, it is the place where one finds oneself. It is not some idealized location. When Paganism is seen from this point of view, the practice of agricultural rituals by urban Pagans starts to seem a little odd. The thrust of such rituals should be to put the place of residence into a greater context, and to relate the life of the city with the life of the rural areas, rather than to express a longing for the rural life.
The cultural side reflects a number of things. There is your ancestry, both genetic and cultural. You came from people, and who they were affects who you are. There is also, however, your present community, both culture and sub-culture. As Pagans we find a role in the Pagan community, but we also find a role in the community as a whole. If we identify ourselves primarily with the Pagan community we reduce ourselves to members of a role-playing game. We must find our place in all the communities to which we belong.
We each live in a variety of contexts -- local nature, cosmic nature, culture, humanity, technology, family, our past experiences, etc. Many religions, such as those of the book, Buddhism, or some forms of Hinduism, de-emphasize one or more of these in favor of other ones. For instance, in many forms of Hinduism, the material is downgraded to the status of an illusion, and not a particularly nice one at that.
In Paganism, however, all contexts are equally valid, although they may not all be as operative in a given situation. For instance, given the choice between doing the right thing for my society and doing the right thing for my family, I don't see any problem in deciding that society doesn't really count. However, each context is equally valid in an ultimate sense.
Just as important as the context question is the living question. People like to say that Paganism isn't a religion, it's a way of life. Although it distresses me that people seem to think that a religion is a bad thing, this is true in the sense that Paganism is not about believing but about doing. It is an orthopraxy rather than an orthodoxy.
So to get to the question of putting what it means to be a Pagan into my own words, a Pagan is someone who lives in all the contexts in which they exist. Not just the eternal context as postulated by the universal religions such as Christianity, but the local ones, the ones outside and inside our homes. It is to find where they belong and then to live that way the best they can.