My husband is Korean Buddhist, and he definitely does not like to randomly kill beasties. However, I am a big wuss when it comes to spiders, and have forced him to become the house spider-killer.
It hurts him to do it, and over time I have realized how much heart pain it causes him, and so sometimes I say that putting the spider outside is OK. Usually depends on the size of the spider and how threatened I feel by it.
We had ants at our old place, and while they weren't causing any harm they were bothering me and our cat (she would freak out if she went near them). So we found some kind of organic powder that had a smell (some kind of spice?) that ants don't like? It doesn't kill them, it just repulses them so they go away. I think some died because we put it in the way of their way out of the condo, which was a mistake we made, but it did eliminate the problem of them coming back in.
We also cleaned the kitchen much more thoroughly than we had been doing.
Over the winter we had squirrels in our attic and were worried about them biting electric cords and killing themselves (and how gross that would be for us, along with fleas, etc), and I was worried about out apt. complexes reaction to it, but they just got some humane traps and with patience got all the squirrels out and relocated to a campground in the area. I was glad (especially being pregnant) that they didn't just run up there with a "bomb" to kill them all.
I'm glad we don't have nearly as many spiders here as we did at the old place, it makes things a lot more peaceful, since I don't have to ask my hubby to do something that sickens him (mind you he was like this even when he was eating meat, which is something I haven't been able to understand yet).