I don't like to categorize, stereotype or group anyone to be perfectly honest. I see myself as me, and while there are other people who happen to have a similar predicament to me as far as gender goes, they are individuals too and very different from myself and each other in many ways.
I don't believe any 'group' of individuals, perhaps grouped as such due to one particular difference, has any specific purpose as a whole. I don't feel I need a purpose in life, I have never felt part of anything big, apart from the planet, which I feel very attached to (nature & the great outdoors) and I don't find this lack of grand purpose in any way frightening, nor do I think it makes me less of a person.
I believe that quite often, people can get caught up in something, such as religion, and feel loss because they do not fit into this odd yet ancient belief of our world. I see this in the same light as the urge I felt to fit in somewhere when I was younger, I look back on it now and hate the person I was because I refused to be myself because it was the hard route to go and I lost so many years trying to deny who and what I was simply because I knew others would not understand it.
I think, in the 'grand scheme of things' you are who you are. The things you do, the paths you choose to take and the purposes you choose to instill in yourself are all dictated by your own freedom of will.
p.s. I think 'Love Your Neighbor As Yourself' as Robyn said, is a good practice to keep, and its the only reason my dad is Christian. I personally am not and never will be in any way religious and I think to respect and love others is just common sense, but if religion helps people to embrace this simple concept, then perhaps its not all bad