i have been instructed by theologians that when in doubt, and unless you can see clear evidence that the bible is using literary devices such as similes, methaphors, symbolism, etc. (just like we do in modern literature), we should take it literally. plain and simple. add that to a decent understandable translation, the bible becomes very easy to understand.
if we second guess god and only accept some of the stories as true, mainly because WE can't imagine how they could possibly be true, we might as well use a rusty bucket full of holes to carry water because that is how much power we will have in our christian walk. do you think the holy perfect being (god) that is described in revelation will mind our picking and choosing what we are going to accept as truth??
there are plenty of things in the bible that have been doubted over the years and they say that every shovel of sand (from the 25,000 archaeological finds) provides more evidence of its truth and historical accuracy. plus, that aside, 2/3 of the 2000 plus prophecies can be proven to be totally accurate and most of them quite specific. that is why i believe the other things that i don't understand.