The officers, judicial and executive, of the government of the United States and the State of Alabama, persons in the Armed Forces of the United States, customhouse clerks, persons employed by the United States in the transmission of the mails, artisans and workmen employed in the armories, arsenals and navy yards of the United States, and pilots and mariners actually employed in the sea service of any citizen or merchant within the United States shall be exempt from militia duty, without regard to age, and all persons who, because of religious belief, shall claim exemption from military service, if the conscientious holdings of such belief shall be established under such regulations as the President of the United States or the Governor of Alabama shall prescribe, shall be exempted from the militia service in a combatant capacity, but no person so exempted shall be exempt from militia service in any capacity that the President of the United States or the Governor of Alabama shall declare to be noncombatant.