[solresol]

China is one of the fastest growing countries for religion both in absolute numbers and in percentages. There are more people living in China who describe themselves as "evangelizing Christians" than there are in the USA, for example. This has been the case for around two decades now.

[fineng123]

But percentage-wise they are the most atheist country in the world, right? That's at least what I thought off the top of my head

[solresol]

Actually, I thought it was Albania -- which was for a while the only "officially" atheist country in the world, but checking up on Wikipedia, once Islam was made legal again, it seems to be back to developing-nation levels of religious activity.

So, yes, you're right, it's China. At a rough pulling-numbers-out-of-a-hat, China will be back in sync with the rest of the world average (for levels of religious activity) somewhere around 2050, when it will be mostly Christian and Buddhist.