Does anyone seriously believe that one day all religion will die?

[Strappado]

But to then go on a mission, spending all your waking hours arguing God's non-existence, in an attempt to enlighten the world into your viewpoint, is daft.

And it's similarly daft for you to try to convince us of your point of view. Why bother?

Throughout all recorded human history, religion has played a part. Why would you then think that this will ever change?

Fallacy. Just because something has been so and so for a long time doesn't mean it's never going to change. Go back a thousand years and imagine everything that people thought were never going to change. The fact is, change is more certain than no change. It just takes time.
Speaking of change, religions themselves are changing to adapt to modern times. Especially Christianity has changed due to external pressure, and if the same can be done with Islam, then that alone is worth the fight.

Darwin taught us that we are animals like the rest. No other animal can change its nature through thought and effort, so then why us?

So you are saying that humans have never changed?

The world will never be united in a single philosophy. And thank god for that (figure of speech).

I agree. And atheism isn't a philosophy. It is fully possible that there will exist a multitude of philosophies that do not have a religious nature.
While I do not believe there will be a single philosophy, what we are seeing today is that the world's cultures are becoming more similar to eachother. Just how far this will go remains to see, but it is happening.