I believe the Bible is God's Word

[Mister Agenda]

It's based upon myths by Bronze Age goat herders

Some stories in the Old Testament no doubt existed for a long time, in various forms, before they were written down. Possibly in the Bronze Age. It's difficult to determine exactly.

It's especially difficult to know who made them up originally. There were goat herders in those days. There were also educated classes who knew a lot more than goat herders, and were writing with various purposes in mind.

If you have some historical evidence showing that goat herders were responsible, that would be interesting to see. 

 which were eventually compiled into written form by Bronze Age priests.

The Bronze Age is said to have ended in about 1200 BC. Recent scholarship dates the oldest parts of the Old Testament to the 6th century BC. So that's a few centuries different. 

But as I say, to make a more effective insult you can say whatever non-literal thing you want. Say it was written by the first amphibian to emerge from the slime, if you want.

I usually say Iron Age. It's more accurate and really not much less of an insult in terms of them knowing a fracton of what we know today about the world and the universe.