In my previous post on Gilgamesh, Richard Dawkins and the “new atheism”, I mentioned how some people have made the claim that the Bible borrowed, copied, or stole certain stories from other Ancient Near East mythology. This argument essentially says that the Bible should therefore not be taken as an accurate historical account, but merely as “Jewish mythology.”
What is the Epic of Gilgamesh?
Considered one of the earliest works of literature, the Epic of Gilgamesh is a Sumerian epic poem which tells the story of a cataclysmic flood, and the salvation of a righteous man on a boat. Portions of the story have been found, which archaeologists date back to 2100 BC. A full version of the poem was unearthed in the mid-19th century, dating back to 650 BC.
Similarities between the two stories
There are many similarities between the Epic of Gilgamesh and the story of Noah and the flood in the Old Testament. The story goes that the god Ea, the creator of the Earth, decided to end all life on Earth with a great flood. Ea selected Ut-Napishtim (or Utnapishtim) to construct a six-story square ark and save himself and a few others.
- God, or several gods, decided to destroy humankind because of wickedness.
- A righteous man was chosen to build a boat in order to be saved, along with some animals.
- Both end with a divine promise not to destroy the Earth again by a flood.
Differences between the stories
- In the Epic of Gilgamesh, the flood only lasts 6 days and 7 nights, whereas in the Bible it lasts 40 days and 40 nights.
- The Bible says that water didn’t only fall from the sky, but came up from beneath the surface of the Earth.
- In the Epic of Gilgamesh, the boat come to rest on a mountain called Nisir, whereas in the Bible the ark came to rest on Mount Ararat. The two are about 300 miles apart.
- In the Epic of Gilgamesh, Utnapishtim received eternal life, whereas Noah died.
Other Flood Accounts
Hundreds of flood traditions have been preserved all over the world, with examples being found in Europe, Asia, Africa, and Australia, as well as both of the Americas, and most share similarities with the Genesis account.
About 95% describe a global cataclysmic flood, 88% tell of a family of humans saved from drowning to reestablish the human race after the flood, 66% say the family was forewarned, 66% blame the wickedness of man for the flood, and 70% record a boat as being the means by which the family (and animals) survived the flood. More than one third of these traditions mention birds being sent out from the boat. 
Who Copied Whom?
If, as ALL these stories purport, we all descended from the one family that survived this world-wide cataclysmic flood, then it would make sense that this story would be passed on and re-told in people groups around the world. Thus, accounts like the Epic of Gilgamesh and others which tell the story of a flood only serve to reenforce the idea that such a flood did take place. Interpretation of why it took place, it could also be expected, would differ as each culture would run it through the framework of their particular religious beliefs.
The biggest question is: which account should be considered the authoritative one, which correctly conveys the facts and meaning of the flood?
For the answer, we would do well to consider the nature of the different texts, and this historicity of other Old Testament writings.
On my trip to Israel earlier this year, I was able to witness firsthand how archaeology is consistently proving that the Bible accurately portrays history. (See: Why Should Christians Visit Israel?) In other words: the Bible purports to tell history (not mythology), and it has a proven track record of doing so accurately.
Given the Jews’ reputation for passing down information scrupulously from one generation to another and maintaining a consistent reporting of events, Genesis is considered by historians and archaeologists to be far more historical than the Epic of Gilgamesh, which is regarded as mythological because of its numerous gods and their interrelationships and intrigues in deciding the fate of humankind. 
Thus, we can be confident of two things: that a flood did happen, and that the Bible not only purports to tell history, but has been proven to do so accurately.
Does the Epic of Gilgamesh undermine our trust in the Bible? No. If anything it bolsters our trust in the historicity of the flood.