Who are the believers of quakerism?

Answer 1

I feel that Quakerism is an approach to worship and life rather than a set of beliefs.

So I guess believers in Quakerism are those who find Quaker worship, sustaining and life enhancing.

This seems a vague answer which is unlikely to be completely satisfying - there are about 25,000 Quaker Worshippers in Britain and hundreds of thousands around the world, although as with other religious faiths there are different styles of Quaker worship.