In a story I've been developing, God has been a sort of father to the human race. He's created them, helped them to grow, and now that they've gotten smart enough to take care of themselves (this is set in the future), He's decided to leave them to their own devices.
This question is similar to How would society react if the existence of a god was scientifically proven?, but with the added event of God up and leaving us behind. There is no apocalypse, no Rapture, no ragnarok, just people living the same lives as before.
For the purposes of this question, assume this god is any god; that is, any religion with a god that didn't turn out to be science was actually referring to this god, and any polytheistic pantheon is just a bunch of different aspects of this god's personality. Also assume that this fact is part of the proof event, so that anyone who is religious recognizes this god as their own. Also, the proof is pretty rock-solid, to the point that only people who doubt the validity of their own perception could ever doubt such proof.
As for the afterlife, there is no word as to whether it exists or not, and whether or not it's sticking around. Same goes for angels/demons/ghosts/vampires/other spiritual things. God just pretty much said "I exist, and I'm leaving, good luck, and we apologize for the inconvenience."
What I'm asking is how people would respond. The religious, the non-religious, young and old, et cetera. What are the short term effects, long term effects, and would things eventually return to normal?
EDIT: By 'leaves', I mean he exits the observable universe, forever.
EDIT 2 (to answer Ayelis's questions) - This event occurs in the present or near future. It is essentially two events occurring at pretty near the same time: one, scientists discover a parallel plane of existence and the existence of a being in this plane who appears to have a lot of power over our universe. They are able to measure that this power has been used on and around Earth throughout human history, and it is theorized that it helped us get to where we are today. Then that being makes contact with us, specifically with every human at once, by manipulating brain waves, and says something along the lines of "yes, that is what you think it is. Goodbye". Then the being detected in the parallel plane disappears, along with all its power. These events are all measured and recorded for future reference. No one is impregnated (except in the usual way).
The god's powers are difficult to comprehend, but it appears as though he exists outside of time and space, but with the ability to manipulate both. Essentially limitless power, or at least as limitless as humans can understand. Jury's still out on whether he could make a rock too heavy to lift.