I am a Christian and I believe the Bible. However, I also believe that much of the Bible, especially the old testament, is more allegory than history.
There is a lot of evidence that "Noah's" flood actually occurred, but it was only in the "known" world of the Mediterranean basin. A land dam at the straits of Dover gave away, and flooded the Mediterranean sea, burying many ancient cultures that lived around the old shoreline.
We’ve had floods since the beginning of time. That’s not a big deal. A really, really big boat with two “reproducing” mates of every species on earth? Pleeeeez...