In Singapore, neutering/spaying is important for cats owner and we have strong supporters from all races and religions. We have Cat Welfare Society runs by volunteers and Pets Villa runs by volunteers, those society helps to rescue stray cats and neuter/spay them.
Why Neutering And Spaying Are So Important 
If you have two breeding cats, and they have 2 litters a year and those kitties have two litters a year each, do you know that in 10 years, there will be over 80,000,000 cats?
And now that you know this, how many do you think find a good home, let alone a home at all?
(Hint: Not many....)
If an excuse of "I can't afford to get my cat fixed" comes to mind, that just isn't acceptable. Lots of animal clinics can do the altering for a minimal charge, and all you have to do is ASK!
There are even health benefits to altering: Spaying a female helps to prevent mammary tumors (and pregnancy as well...). Plus, spaying stops the rolling and howling that females do when they are in heat, which can be annoying!
Neutering a male helps in the prevention of testicular cancer(and of course, unwanted litters). Neutering also prevents spraying (phew! yuck!) and the desire to roam.
Some people say they have found homes for their cats' litters. That may sound great, but for every kitten born, about 5 die in a shelter. That kitten who died could have found a home with that very someone who decided to get one of their friend's litter instead of saving the kitten from the shelter. That poor kitten didn't have a chance in the world.