Trouble is, I suppose, that Draft Boards tend to want evidence that you have such a belief, and membership of a pacifist faith provides that.
They can't just take your word for it, or anybody would be able to claim exemption. It may be possible to find other evidence, but probably a lot harder.
There's the example of Israel, which in theory has universal conscription. The Supreme Court recently ruled that refusal to serve for being a conscientious objector was permitted (though selective service - e.g., serving as an ambulance driver like some pacifists do in some countries) is
not. It's also worth mentioning that Israel has no "unarmed soldiers" - medics, ambulance drivers, surgeons, chaplains, etc are all trained in weapons and armed in general (though those not in combat units don't carry weapons day-to-day, which is true of all such soldiers). On the other hand, less than 10% of people who apply for conscientious objector status actually receive it, and most that do have family political connections. On the other other hand, refusal to enlist is typically punished by a prison sentence of about the length of service (I
think in military prison, which in many ways is like all the boring parts of being in the army).
As an aside, there
are lots of ways to get out of serving in the military. For example being ultra-Orthodox, a "regular" Orthodox woman, a married woman, Christian Arab, Muslim Arab, Bedouin (all legally different groups), or actually being physically or mentally unfit; though note that there are ethnic/religious minorities that
are conscripted such as the Druze or Circassians. The favored way for "regular" Israelis is to have themselves be declared mentally unfit. The IDF is usually fairly lenient in these cases, since as an organization it's fairly sensitive to mental health (suicide is terrible for morale). For girls, a sham marriage is also pretty common. Note that there's fairly powerful social pressure not to "draft dodge", though people still do it - this stigma is actually great enough that people who legitimately are qualified not to serve (e.g. physical disabilities) sometimes lie in order to enlist.
