You can simply ask and fill the Conscientious objector status procedure, if the search fonction was available i could have link to a previous thread initiated by me.
Duke Of Malbrough have post good links about this legal procedure. ( Can he post them again, please)
In brief, if for a religious,moral or ethic reason, you dont want to kill a human beeing, then you will have a honorable discharge, but i tell you, be sure to follow every step of the procedure, so get information before you are draft.