a·the·ism 
(āthē-ĭz′əm)
(āthē-ĭz′əm)n.
Disbelief in or denial of the existence of God or gods.
[French athéisme, from athée, atheist, from Greek atheos, godless : a-, without; see A-1 + theos, god; see dhēs- in the Appendix of Indo-European roots.]
athe·ist n.
a′the·istic, a′the·isti·cal adj.
a′the·isti·cal·ly adv.