In the words of William L Rowe...
"An agnostic is someone who neither believes nor disbelieves in the existence of a deity or deities, whereas a theist and an atheist believe and disbelieve, respectively. In the strict sense, however, agnosticism is the view that humanity does not currently possess the requisite knowledge and/or reason to provide sufficient rational grounds to justify the belief that deities either do or do not exist. In so far as one holds that our beliefs are rational only if they are sufficiently supported by human reason, the person who accepts the philosophical position of agnosticism will hold that neither the belief that God exists nor the belief that God does not exist is rational."