On the first day, Lucifer rose. God looked down upon His lost son and felt like eternal damnation was possibly an over-reaction to a teenage rebellion. He saw the devastation wrought by the Morning Star and He saw humanity quake at the Devil's presence. As has been written, He prepared himself to cleanse the Earth once again of Evil but stopped when Sam Winchester stepped forth and declared, "I got this."
On the second day, the war was vast and bloody. Mountains trembled, seas raged, and thousands of demons fled back down to damnation under the weight of Sam's stare. God watched some more of 'Dance Your Ass Off' and He saw that it was good.
On the third day, the angels fled. The archangels came before Him to announce that the war was going well, even with their absence. For they had not been cowed at the sight of Satan but had been banished by Sam Winchester. An angel of lower rank had dared to make bedroom eyes at Sam Winchester's brother and so their brethren had retreated when Sam claimed that "he wouldn't stand for this shit." God thus yielded and commanded the angel Castiel to keep it in his pants.
On the fourth day, Lucifer was vanquished. The four horsemen retreated back into Hades, the cries of the demons were silenced forever and order was restored to the world. God celebrated by purchasing a Slap Chop and spent the evening attacking His food with ninja precision.
On the fifth day, Sam Winchester fucked his brother. God thought about objecting but Dean Winchester seemed pretty happy with the arrangement and God decided that He could overlook a little incest now that the world wasn't ending. He watched proceedings for a short period and may have rubbed one out in private when Sam took Dean from behind on the hood of the Impala.
On the sixth day, God came to Earth. His arrival coincided with the season premiere of Gossip Girl so very few people noticed. He made Himself known to Sam Winchester and offered His divine congratulations on defeating Lucifer and on displaying an impressive sexual prowess the day before. So He spoke, and Dean Winchester turned pink in embarrassment. Sam shot Him a confident smirk and He requested that the Biblical narrative omit the following events.
On the seventh day, God rested.