If you don't like cats, that's fine. Please continue.
If you DO like cats and think your cats are beautiful perfect fluffballs that never mean anyone any harm, that's fine. Please continue. (Also, never get them vegan catfood. It's arguably a scam and if it isn't, it will do them actual harm. Cats are carnivores that cannot survive without meat. If you are uncomfortable with this, please do not own a cat.)
So, the main religious argument between cat owners - indoors vs outdoors. (And it very much is a religious argument - in that both sides have valid points and neither side will ever convince the other) I come down firmly on the "indoors" side of the argument. If you never let a cat get outside, the cat will not WANT to go outside - its territory is the same space as your living space. It will patrol it and watch for interlopers and walk alongside you as you go about your day. Cats are territorial beings, and you have helped establish your territory as their territory.
Whereas outdoor cats - once you let them outdoors once - JUST ONCE - you will never be able to stop them, ever again. (Cats are more clever, and quicker than you are. It is known.) Their territory is now as far as they can roam. And roam it they will.
The problem is when those come into conflict. Specifically, there is a neighborhood outdoor cat who has taken to specifically teasing and tormenting my indoor cat. S/he will remain outside HER window, hissing, teasing and otherwise establishing dominance, and all my cat can do is get EXTREMELY upset.
I'm thinking I need to get some sort of cat repellent scent for my back yard. Or perhaps a sturdy stick.