Malthus was temporarily wrong at best. You are taking an extremely narrow slice of human history and extrapolating the future from it. Without a controlling global enforcement of birth control (none currently exists and undoubtedly won't any time soon), then those who don't use birth control (whether driven through cultural or biological means) will have more fecundity and quickly outbreed and replace those that do. And if everyone is guaranteed equal sustenance and resources it will very quickly devolve into a Malthusian situation.
tl;dr Give everyone and their offspring guaranteed sustenance and the Catholics and Nigerians will take over in a couple generation. Nothing about the OPs post said give everyone enough wealth and force birth control so that they only reproduce at a replacement rate.
Not if the LDS Church has anything to say about it. I can't speak to the fecundity of the modern Nigerian family, but I'd wager the average American Catholic family is smaller than the average American LDS family , and by significant margin. Anecdotally, a former colleague (an LDS member) recently welcomed his 11th child. Apparently, a family with 11 kids was neither extreme nor unusual in his ward.
Hah, yea I was just going with Catholics since they've been burned into the collective conscious as anti-birth control. Seems most of them don't actually listen to the Pope much these days.