In the current environment, I should think that being an atheist in the service is about as hard as being gay in the service. You'd be surrounded by believers, though of course seeing a buddy blown up by a IED might shake the faith of some. (Then you could explain to those around you, "If God is omniscent, omnipotent and good, why did he allow Billy to get blown to bits?" The answer of course is always, "God works in mysterious ways." To which you might add: "If God is on our side and the other guys say God is on their side, one proposition being true, maybe their God is more powerful than our God." Hopefully, they would eventually see the absurdity of belief.
The most preposterous notion that H. sapiens has ever dreamed up is that the Lord God of Creation, Shaper and Ruler of all the Universes, wants the saccharine adoration of His creatures, can be swayed by their prayers, and becomes petulant if He does not receive this flattery. Yet this absurd fantasy, without a shred of evidence to bolster it, pays all the expenses of the oldest, largest, and least productive industry in all history.