Particularly the story we're celebrating today about a virgin giving birth to a child
In fact, as an engineer one of my biggest difficulties with Christianity is the idea that the natural order of the world could be disrupted. That the rules of the universe could be broken. I spend months processing this concept, thinking "I can work with the idea of God - the universe exists, so it's at least reasonable that something created it. But the virgin birth of Jesus? There's gotta be a better explanation. Something that fits within the framework of rules that I understand the universe to follow...".
Surprisingly, my breakthrough in understanding also grew out of being an engineer. I realized that if I imagined God as a computer programmer running a simulation called "The Universe", miracles didn't sound so outlandish.
Why does this change things? Programmers have a tool called a "Debugger" which lets them arbitrarily pause or modify a program while it's running. The program has no idea it's being modified. Even the most absurd miracles like the sun pausing in the sky (as famously questioned by Inherit the Wind) seem possible.
<GDB - God's Debugger>
# sleep(3.5 billion years)
# sleep (1 day)
This visualization allowed me to consciously separate the question of could this happen? from did this happen?. This separation in turn allows me to take a concise stance on many of the big ticket questions Christians often face:
I believe God created the universe with a set of consistent rules. I believe that God can alter the universe in a manner which is entirely unknowable to anything within the universe.
On questions of the nature of the world I defer to scientific reasoning, holding in reserve the notion that God could have modified the state of the universe in any way at any time.
Examples of the application of this stance:
Evolution: Based on the world I see around me, evolution makes a lot of sense. Most scientists who study biology agree. God might have created humans exactly as we are now, but we have no way to know whether that happened. It's not a big deal - either God created the universe with a set of rules that brought us about, or God created the universe, paused it, and injected humanity directly. The world looks the same to us either way.
Noah's Ark: I would not be surprised if this story (along with many others in Genesis) is effectively a fairy tale, passed down between generations as a means of describing God's character. It certainly reads like a fairy tale, so I'm content to say maybe it happened, maybe it didn't. I don't know, and I likely can't know.
So, why believe any of what's in The Bible?
The answer to this question hinges on the notion of a Living God. That is, understanding God to be an active, engaging presence in the world today. I have had a variety of experiences which left me with the feeling that God was actively engaged with me. These experiences largely center around communities and beliefs of the Christian church, which use The Bible as its principal guidebook.
I italicized feeling because I acknowledge that this could all just be a feeling. I don't know. However, trusting and pursuing that feeling has yielded love, community, and insight which together reinforce and reaffirm my decision to continue to pursue God.
My wife and son will probably wake up soon, so I'll end with this: