How do you grasp the idea that something has always existed?

[Takes_Two_To_Tango]

Nothing is created or destroyed it just changes forms.

 

[Sarge3000]

There is nothing wrong with admitting that there are things you don't know. It is actually an indication of intelligence. The Big Bang Theory comes from observations that everything seems to be moving away from a point in space. I would be like you standing in a spot and being hit by a snowball. You could probably figure out what direction it came from but not the exact point or who threw it. From the direction something is moving we infer the direction it came from.

Some theories might explain a Big Bang but leave more unanswered questions. As humans, we see things having a beginning and an end. There were things humans once thought were constant, like the Earth, Moon and Sun but we realized that everything changes.

I think how the universe was created is the same why our planets were created and mankind eventually came to exist.
Mankind came from bacteria in the water (if I remember correctly). Our entire planet used to be mostly water, from bacteria in the water came creatures that crawled to the earth, then monkey/apes, and finally us.

These are all clearly identifiable and logical biological processes.
I think what most humans can't accept is that there is no big reason behind it all.
But I don't think that's so depressing. I think the fact we came from such a long way and the abilities of humans to produce such greatness (art, science, etc) is inspiring to live and go on in itself. Why the need for a creator? Some big dude sitting on a throne in the sky? Come on.

I think the entire universe, us included, are just part of a giant biological process that never ends and produces life and death and it renews itself without end.