There's already too many humans on the planet. A reduction would be really welcome. Humanity can't keep growing forever. The planet can only sustain so many. I think a reduction will actually stave off disaster though in terms of climate change we're already too late.

I don't think the reduction in birth rate has anything to do with religion and a conservative religious society sounds like a nightmare to me personally.

For me the reason for not having kids is simply that life is already expensive enough even with a double income, and life is much more fulfilling without the responsibility of having to raise kids. I've seen so much of the world that I wouldn't have if I'd be rushing between work, school and judo clubs.

I think it's a really good thing that people no longer have to have kids for economic / pension reasons (or lack of decent contraception) but just have them if they really want to. Personally I don't and I don't think I'd be a good father so it's better not to have them.