First, this has nothing to do with atheism. At all.
Second, it's entirely possible that true randomness exists, on a subatomic level.
Three, with an average home PC, although you can follow the design and manufacturing process all the way through the end product may as well be magic - it's very hard to comprehend. Now think of brains in the same way; they're the single most complex thing we know about and although you could come up with their build down to the individual neuron, in the same vein as a home PC but magnitudes more they're basically magic.
And by magic and I mean 'good fecking luck understanding it'.
An electromagnetic (or whatever how's that being slept) kind of force. There's two types. One that has a negative force, another that has a positive force. When both come nearby (both being different) they pull each other. Why does anything that is made from metal fly towards it? Because its made of metal.
...no. Just no.
I'm not going to explain it but you should be looking to fields and the like, not...two forces...it's one force. They don't just 'pull each other' when they come nearby, go to fields again.
And finally, it's only iron, cobalt and nickel that can be magnetised, and no it's not because they're made of metal, it's just a tad more complex than that.
FFS if you want to actually know the answers go look it up on wikipedia or something, I'm giving you an F for how bad that was.