Basically, we are nothing but decaying tissue.
But humans have such a desperate need to believe in something greater than themselves - that they have a purpose, that they are special. Humans want this so bad they alienate one another by creating different religions where their 'God' picked them. In the end, we're just the same as the rest of the animals on this planet.
It isn't as grim as all that though. Personally, I see our 'purpose' as our children and, to a lesser extent, each other. What makes us 'special' is how we conduct ourselves in everyday life. Principles, morales, friendship, love and family all stand together worlwide without the need for an afterlife. It is only the need to believe that makes us often associate these things with religion.
Anyways we all believe in something. Some say they're nihilistic when really they just believe in not believing, while a lot of people just believe in believing.
I myself believe in death without an afterlife - that Heaven & Hell is a superstitious concept made to try to keep people in line.
And really, a God who loves all and forgives all, slams the door in your face?!! WTF is that all about? It's about getting you to join 'their' group, give 'them money' and praising the Lord for every Jew at Auschwitz and for every baby born HIV positive.
Death is resting in eternal peace, without God, without hate, without divisions.
Nothingness.