Gee, the story seems to have some holes in it. As Neopagan pointed out, A&E lacked access to modern theological thinking, so they had no one to advise them on the specifics of the banned tree or to explain the long-term consequences. Because not only did they not know about lying, nor death, but they also lacked any realistic concept of time. And as epidemic said, they had no way of understanding how being bad (not understood) would permanently alter the state of human affairs. Nor were they given the complete story. Had god said "Hey, if you eat from that tree, I'll eventually have to drown most of the planet, rape a virgin and have myself a kid that I'll then have to kill, then wait around a few more thousand or tens of thousands of years or whatever to send him down again and save the planet, and it would just be easier if you would not eat from the tree that I so carelessly put there."
At which point, A&E could ask a few questions, like "What is lying, what is death, what is eventually, what's a planet, what is drown, what is rape, what's a virgin, what's a kid, what is killing, what are thousands, what are years, what is saving and what does careless mean?"
The dude took the time to sit down with Adam and name all the animals, but he couldn't spend ten more minutes with the innocent couple to explain things a bit more clearly? He couldn't have couched the problem in a more meaningful way. Like taking them to the edge of the garden and showing them the desert or whatever was beyond (they got cast into something, so I'm guessing it was a little less desirable) and said "Do as I command and you will get to stay in this beautiful place with that tempting tree forever. Eat from the tree, and you have to go live out there where it is dry and there are few trees to eat from and stuff. I am testing you, and I have no tolerance for failure. Even though I'm infinite, I have a tiny mind and no imagination, so you guys are kind of up sh*t creek without a paddle, a concept you'll never need to have explained if you just stay away from that tree. And by the way, there is a serpent crawling around the garden that talks and he'll try to convince you otherwise, but don't listen to him. If you do, out you go, and I'll have to write a big long book full of silly stories and inconsistencies that will fuel thousands of years of warfare, and I'll have to do it without a word processor because its too early for that."
"And by the way, kids, I know you'll fail because I'm omnipotent and I didn't take any preventative measures when I designed and built you two from mud and bone. A tiny adjustment to genes here and there and both of you would be completely complaint. But that would be too responsible of me." sayeth the lord.
Little tip to theists: Silly stories should be a dead giveaway. Its all fake.