The problem is that the distinction between groups of people who belong to a "faith" and those who do not can be a divisive one. All people believe in something, but certain people are given greater (or lesser) respect because they belong to a "faith". This creates a value driven classification of people which I think is ultimately divisive. It also produces a strange sense of relativism - emphasised by Prince Charles' claim to be "defender of faith" - irrespective of whether any particular faith is true or not...As an Anglican I am all too conscious that I don't belong to a coherent system of belief - or an organised religious movement. While Methodists have their committees, the URC have documents and the Catholics have papal authority, we Anglicans have been at our best when we've embraced variety and diversity - it's possible to be an Anglican and believe or do pretty much anything - within reason. We're neither coherent nor organised and our attempts to become so have usually gone badly...
The word belief is a little better. Even atheists have beliefs. In fact the truly committed atheist needs to have a great deal of belief since he or she needs to believe in the non-existence of something on the basis of very little evidence that this thing does not exist. We could therefore talk about beliefs and believers - although this may penalise agnostics and the apathetic who don't know what to believe in or can't be bothered... and atheists may not like being called believers...I prefer the term world-view. We all have a way that we understand the universe and the way things work. We all have a sense of how we want things to be or a set of values that we feel are important. We might not act on the basis of our world-view but we do have one. This term doesn't imply anything coherent or organised. It isn't divisive or derisive. It would be possible to speak about "people of all world-views" - and really mean everyone.
Language is important and it actually affects the way we think. This is my suggestion for a piece of sensible language use that would genuinely promote equality and diversity - although that may be my world-view so don't feel you need to agree.
