Most people these days have been sold on the idea that the entire universe started with a big bang.

I love the big bang idea for the very simple reason that it gets people to ask questions. The most common being, what came before the big bang? 

We will get to that shortly. But lets ask the same question, what came before the big bang? from an historical point of view, by this I mean, what did we believe before we were sold the idea of the big bang? 

Let's ask a few more questions .

where did the idea of the big bang come from? 
What is the Big Bang? how did it get its name? 
How do we know it happened? What is the evidence? 
What does it mean for us if this theory is actually correct? 
What does it mean if the theory is wrong? what happened if the Big bang didn’t happen?