If you're set on not killing yourself I'd invest heavily in companions to do the work for you. As it was already mentioned in this thread, the FoA have armed guards in their places of operation. Arcade and Rex would be the obvious choices.
That said I don't think it's really necessary to *not* kill to roleplay a Follower. You'd probably just end up killing raiders such as the Fiends and the Powder Gangers and there's no real moral obstacle there. In fact, dispatching those kinds of groups would probably be quite in line with the Follower's views.
Mostly why I pointed out the companion/temp companion option.
Largely the issue is that the Followers frown on bloodshed and there's really no quests dealing with large corruption with the FotA and rather it's not as in tune with the NCR as they would want.
The only irony factor comes with Edward Sallow, aka Caesar. That knowledge in the wrong hands can be deadly and that FotA created themselves the antithesis to their values.
Still I'd say a fully pacifist route is the most challenging and rewarding.
Your choice.
But again OP, your personality doesn't have to be kind nor be a sissy. That's where individual uniqueness comes in. As long as you stay true to FotA values, such as providing to those in need or in bad condition, and make sure violence can be undermined your free in perimeters.
And doing that doesn't always mean "good" outfits like the NCR will like you i.e. Sparing the enemy, or helping them from cruelty.
Also note in the 4 MQ paths while self pacifism is supported there's no way to stop NPCs aiding you from killing the opposition.
Some people think pacifism and being a FotA means having the power to stop all deaths as well. Not possible.