So far the US military has limited religious accommodation to established religions and their known rites. Not just the big three, but also faiths like Wicken.

They don't accommodate somebodies "one-off" religion that they just made up on spot for the sole purpose of shirking duty or stirring the pot, nor would they take seriously an obviously farcical religion like "pastafarianism".

IMO athiests need no special accommodations because that is not a religion or faith, merely a lack of one. Don't believe in anything at all? Well you don't need to perform rituals to celebrate it, so get back to work.

Nor do we need atheist chaplains...atheists can get whatever non-theological counseling they need from regular chaplains...their faith won't hurt you if you don't believe in it. Or else they can go to medical, family-service, etc. But a person of faith who ends up being ministered to by an atheist "chaplain" in a time of great need would probably feel something was missing. How can one get religious support from someone who doesn't believe in it? That's like using ISIS to monitor elections in a developing country...