More likely to disappear, atheism or all religions?

Humans would have evolved into something else by then so the point will be moot!

At the current rate religion will be completely gone within 150 years max. No need for a billion.

Atheism isn't naturalism. It doesn't really have anything to do with naturalism. It's simply the lack of belief in deities. That said, atheism isn't "something" that can disappear. It's a lack of something (i.e. a lack of theism). So the answer is religion.

Well, if current trends continue religion will be extinct by the end of the century.

Clearly all religion.

Ignorance will never stop...

And when there is either one atheist or one "religious" person (and like most atheists you successfully confound believing in God with participating in a religion, which is wrong) left in the population, will you evaluate this as one side having disappeared? Belief systems are dynamic. Like in most cultures beliefs and values change over time, it does not mean that they disappear. If you're talking about the whole world, belief that God exists will never disappear. If you're talking about a culture, like in the USA or Canada, you will only find change over time. There will always be both believers and disbelievers. If one side outnumbers the other it makes little difference, as you can see with atheism right now because it survives. In places of harsh authority against religion, belief that God exists still survives there as well.

i was going to say none but ryan's point is good. at this rate, religion.

Well "atheism" really isn't a thing. It's not a construct or set of beliefs. It's not a hobby or even a concept. It's really just the default we're all born with. One has to learn about religion. So religion, though not likely, COULD disappear, while atheism can not.

Trend shows superstition, thus religions.