Three US Navy sailors from the USS Nimitz told reporters they were victims of discrimination after being discharged over their desire to observe the Sabbath:

Cedric Davis and his brother, Tracy, both served just shy of their four year commitment. Graig Mitchell served for a year and a half. They all received a general discharge weeks ago, all because they said, their commanding officer didn’t respect their Seventh Day Adventist faith and the day of worship.

The article doesn’t get into specifics, and there is no response from the Navy.  A “general discharge” (which falls into the “other than honorable” category) does seem to indicate their service was viewed as less than exemplary.  To be frank, its unclear how they lasted that long.  It’s surprising they got through boot camp without issues while religiously observing a Sabbath.

This has been addressed here before, in regard to Christians who may feel they are being denied their religious exercise by being forced to work on Sunday. 

No matter what your religious beliefs, if you are a member of the US military you will, at some point, be required to work on Friday, Saturday, or Sunday (along with every other day of the week).  While DoD policies require the military to accommodate religious practices, that requirement extends only to the point it affects the mission.  There may be some room for maneuver in garrison/port/at home base, but particularly in a deployed environment, the war doesn’t stop — and the mission doesn’t pause — just because it is a particular day of the week.  

If a person holds a religious belief that requires observation of a Sabbath or equivalent day in which they believe they cannot perform a military mission, then they probably shouldn’t join the military to begin with.  If, while in the military, one converts to those beliefs, the best course of action is to serve faithfully until given the opportunity to resign.

If one cannot faithfully serve, then the consequences of those choices must be accepted.

It is by no means perfect, but the US military generally does an admirable job of trying to accommodate the religious beliefs of its troops.  (Indeed, there are Seventh Day Adventist chaplains.)  But it can’t accommodate everything and still perform the mission.