What I typically mean, when I say atheist, is someone who was at heist, or was at least present, when stuff was stolen.
An agnostic is someone who is "ag no stick", which means that silver will not stick to him. Typically, this is a vampire, or werewolf who has super powers, to avoid being skewered by silver crucifixes.
An agnostic atheist, is a super vampire who was at the heist, to obtain any spare silver, so that they could hunt stupid vampires, or start a colloidal silver shop on ebay.
Typically, an agnostic vampire has acquired his immunity to silver crucifixes, by Buddhist meditation, so as to achieve a total lack of belief in God. Stupid vampires who believe in God, tend to die when skewered by a silver crucifix.