I consider myself a non-believer. In this I simply do not have a belief in whatever the object under consideration may be. In religious terms, I am an nonbeliever in God.
I consider this different from an unbeliever. In my philosophy, and unbeliever is the opposite of a believer. A believer has a positive believe in the existence, truth or validity of the object of belief. An unbeliever has a positive belief in the non-existence, non-truthfulness or invalidity of the object of belief.
I would equate an unbeliever with an atheist. However, in a needless act of splitting hairs, I do not view non-belief as the same as agnosticism. As the believer positively believes in the existence of, the athiest positively believes in the non-existence of, the agnostic postively believes in the inability know one way or the other. The non-believer just does not care and has no belief one way or the other.
Existentially, the existence or non-existence of the non-believed in object is irrelevant for the non-believer and does not matter, whether or true or false. The non-believer may find the arguments for or against belief interesting and even intellectually compelling, but inevitably these arguments are simply an exercise in analytical thinking and metaphysical inquiry. They aren't, however relevant, and so do not factor into subsequent decision making.
Believers and unbelievers will deliberately construct other elements of their philosophy and life's vocation from the belief they hold. For non-believers this is not necessary.