Imagine a vast, clockwork machine. It has millions of finely detailed cogs and levers pulling and pushing on each other. I want you to imagine it is as beautiful and complicated as you can.
If we watch the machine we see the cogs turning and the levers pushing, but it doesn't have any purpose. It runs and ticks, the wheels and cogs spin and turn and the levers push and pull in complicated ways but all without purpose. It will continue to tick pointlessly until the day it breaks and stops forever, having done nothing except spin its cogs and push its levers. As far as we can tell the machine came from nowhere and having done so ticks in futile purposelessness to an end, all for nothing.
That is only an initial at a metaphor of the universe - no doubt it can be criticised and improved! The point it that I can imagine there are people who can and cannot accept it as a metaphor of the universe. If you can then you are probably an atheist - I suggest typical theists cannot accept that the universe is a pointless mechanism that runs for no reason with no purpose, no meaning nor goal to it.