According to the Bible, it took Noah 40 days' and nights' labour to build his ark. For 40 days and 40 nights it rained and Noah was at sea. Jesus Christ spent 40 days and 40 nights in tribulation in the Sinai desert with Satan.
See the pattern?
No, I haven't gone all Bono on you (yet); but isn't it interesting to note? Christ himself was reputed to be alive during the reign of Emperor Julius Caesar, and the Julian calendar was not introduced until shortly before the end of his reign, let alone today's Gregorian calendar. Therefore, during the account of the Biblical stories, we can assume the phrase "40 days and 40 nights" meant a substantial period of time, perhaps ambiguously conveying a period longer than a month but shorter than two.
Where am I going with this? Christians believe God made the world in seven days, but has a day always been the same length? In the same way as the timescale may be subject to change, accounts of events the Bible will be different, written and revised by different people. In no way does this make me, as a person with Christian beliefs think that the Bible is fabricated. I am simply saying that stories (Biblical ones in particular) have a moral derivative.
I am not saying that one aught to disregard the more serious topics of the Bible. It's all there: rape, prostitution, incest, murder, blasphemy, sodomy, sin. This is why certain topics are 'glossed over' for some audiences if you like. You may remember learning the tale of the Good Samaritan in school perhaps, but not the tale of the children who mocked Elijah and were subsequently torn apart by bears. Cruel, yes. An act by a loving God? I believe, still, yes. The moral grounds are there - forsake the Lord and there are repercussions. In the same way, a murderer is breaking a commandment of God and subsequently goes to Hell. Perhaps to be torn apart by Demons (OK, I'm getting a little presumptuous here).
Think back to The Simpsons (I never thought I'd here myself say that during a theological argument), and Homer's holographic picture of God; on one side, God smiting humanity, on the other God grinning with his thumb up. As a child I was never shielded from the actions of 'vengeful God', I was encouraged to read my Bible and I did; my leaders were well aware that I would find things I didn't understand, didn't dare to imagine and perhaps didn't like. As they probably did and still do.
I can't pretend to have all the answers. I don't even think Atheists have all the answers to oppose God - "Why did God create us?" is a good example of that. In this lifetime we will never know.
Think of it this way: we will never know the secrets of life itself, any more than we will know the exact height of Goliath or whether Samson would ever endorse TresEmme. But God set out a helpful guide to show you how things roughly balance out.
For a bit of extra reading, try this: it's quite interesting: