Prothero outlines a very straightforward approach using four bulleted points to outline how each religion differs from another.
* There is a problem.
* There is a solution to that problem, which also serves as the religious goal.
* There is a technique from moving from the problem to the solution.
* There are exemplars who chart this path from problem to solution.
He goes on to define these terms for two very easy to define faith traditions.
Christianity sees the problem that humanity faces is sin. We are all fallen short of the glory of God. The only path to redeem ourselves of sin is through salvation through Jesus Christ. The techniques of salvation vary from tradition to tradition, though certain things like baptism, confession, and communion have a tendency to crop up among different facets. Exemplars would be saints, charismatic leaders, Jesus himself, etc.
Buddhism sees the problem that humanity faces as suffering. We are born into a world of pain and suffering and only death releases us, but reincarnation brings us back into this world and the cycle repeats over and over again. The technique is to achieve enlightenment and break free from the wheel of rebirth. Buddha and Bodhisattvas have given us different techniques to achieve enlightenment if we would follow their example.
And ever since I read that I feel like I have floundering for an answer for Paganism, and to be perfectly honest this is probably my biggest hangup when people drop Pagan and say Polytheist. To say you're a polytheist doesn't actually say anything meaningful other than you have loads of Gods. But WHY? That's what I want to know.
Perhaps this is why we're all kind of wandering around and wondering what the hell our elevator speech is. Without being able to define the purpose of these devotions we just are doing things because they're done. Empty ritual serves no purpose, and doesn't really lead anyone anywhere.
Other polytheisms can look at their function and explain why we do these things. Hinduism has the concept of moksha which is similar to the Buddhist attempt to break free from continual rebirth. You either obliterate, or you become perfected and like unto a God. It's kind of a tossup really until you work your way there by cleaning out the karma closet and doing all that Bakhti to the God(dess) of your choosing.
But why do NeoPagans do what we do? What is our problem?
Can we point to a fundamental flaw with humanity and say this is our problem, and these practices are our solution?
I go back to Michael York's comment that paganism tends to be "spiritually materialistic." The purposes of ritual actions are for favor from the Gods for something right here on earth. Because this is where LIFE is. The Religio Romana has a very strong emphasis on the individual's place within all these layers of superstructures (Home, Family, City, Nation, etc.), defining the ripple of influence should the devotee receive favor. The purpose of doing devotions to ancestors, on the surface of it, is the hope that the same is done for you when you pass over and so that you are not forgotten among the living. The dead are 99.99999% of the time just shadows. A few, very rare, and exceptional people are ever exalted to the status of God. Most of us poor saps are just right here living to live and trying to make something of ourselves. Perhaps the problem is that life is brief and death is so long, that we seek to make what we can of this life and progress ourselves and our families through the favor of the Gods. Is it enough to be performing rituals for the sake of maintaining a personal legacy? Who will pour wine on your grave?
Then again, that's not everything. That's just a kind of Neo-Classical worldview. Wiccans would probably say something entirely different. That our problem is that we are not connected to the cycles of life and death, and that by living the wheel of the year we come closer to living in harmony with the world. But what does living in harmony get us? Recycling back into our families? Happy smiles in a summer land?
I think of all the traditions I know Thelemites are the most developed to answer these questions. They would say that the purpose is to understand your true will and purpose here in this life to accomplish the Great Work. Though from there it kind of goes fuzzy. What happens once you start living in concert with your True Will? Where does that whole business wind up going? Is there an ultimate end goal beyond KCHGA? Perhaps I just don't know enough to answer that question.
So, What is the purpose of your faith? What's the problem, and how does your faith fix it? Is that even the right question to be asking? Perhaps this is all too personal, and that each person's rituals serve a purpose unique only to her. I don't have answers here, and I think it bears raising the questions.