But of the tree of the knowledge of good and evil, thou shalt not eat of it: for in the day that thou eatest thereof thou shalt surely die. Gen 2:17
Adam and Eve didn't die the day that they ate the fruit. Either God lied or he is not all knowing. I'm sorry for being blasphemous, but I believe it should be addressed.
In the day you do this, you bring the death penalty on yourselves. Doesn't mean the sentence is exacted, but rather that sentence is passed on that day.
If you contract terminal cancer you will die. You don't die the day the Dr. finds a shadow on the X-Ray, but rather, the day the Dr. finds the shadow on the X-Ray, you know you are going to die.