Two gods were sat in a New York park one day. Being deities from two different faiths, they were arguing as usual about who was the most powerful. Such arguments were common between gods as each wanted to prove they were better than the other (the past thousand years has seen a fast increase in such arguments as one by one, each god was slowly being forgotten about by the humans they watched over).
The two gods in question this day were Loki and Asiaq. Since the fall of the Nordic and Asiaq religions respectively, there really had been nothing at all to do for either of them. When Loki sent Chlamydia down to Earth to screw with the promiscuous classes, nobody prayed for him to take it back. Instead they wrapped themselves up in latex and blamed the disease on the Europeans. Likewise when Asiaq brought forth great storms and winds to beat down upon the humans' homes, the people once again did not pray to her, they gave the winds names like Fred and blamed them on Henry Ford.
For the average man or woman it would be irritating to not be given the credit you deserve for such hard work, but when you are an immortal and this has been happening for hundreds of years... well eternity can really begin to drag. A god without followers is like a junior banker in 2009: redundant. Thus one has to resort to petty bickering and squabbles amongst themselves for any sort of recognition of their powers and glory. This in turn has led to the rise of the inter-deity wager.
Even though the arguments had raged on for centuries, the first such wager occurred in 1883 when Ra, the Sun-God got into a quarrel with the fire-god: Zhu Rong. Being one of the original great gods and lord of the greatest empire the universe had ever seen at the time, Ra soon became angry when Zhu Rong claimed that his time in the sun was gone for good. Zhu Rong chided him that gods such as Jehovah who were still all-powerful with followers controlled the sun now and as such he was now irrelevant. Such talk had angered Ra and so he issued the first ever inter-faith challenge to Zhu Rong. He boasted to Zhu Rong that his power over the sun was as powerful as ever and to prove it he bet Zhu Rong on a set day, he would be able to bring darkness to a specific part of the world for longer than Zhu Rong could.
Zhu Rong accepted the challenge and the terms of the wager were set: On the next day, Ra would attempt to bring darkness to Europe for as long as possible before Zhu Rong would be charged with trying to beat Ra's target. The loser would become the winner's slave for the next thousand years.
When the day of the challenge came, deities from all over the Earth gathered to watch the spectacle. Ra was unfazed by the crowd and when Zeus (who had been appointed referee) signalled, he began the challenge. The onlookers watched as Ra summoned up the whole of his power to push the sun behind the moon and cause an eclipse that did indeed plunge Europe into darkness. Ra's success was short-lived though as soon the gods of Christianity and Islam saw what had occurred and quickly brought Europe back into the light and Ra's challenge was over. Ra had achieved a time of just nine minutes, but he was not bothered. There was no way that a mere god of fire could better him.
The next day, the crowds once again flocked to see the second half of the spectacle unfold. Nobody gave Zhu Rong a chance in Hades of winning as none could see how a fire god could ever bring darkness. Zhu Rong was not fazed though, he had a plan and once everybody was in place to witness this historic event, he began:
At first it seemed like nothing was happening and Ra began to mock his opponent and encouraged him to just give up already. Zhu Rong however just smiled and pointed to a small island south of the Asian mainland. The spectators turned and watched as the island off-Java exploded in a cloud of ash and fire that billowed endlessly into the sky. Like the day before the modern gods saw the carnage in Krakatoa, but there was nothing they could do, to stop things now would require interfering with nature and that would not do. On that day, Zhu Rong successfully brought darkness not only to Asia, but the entire world and for much longer than nine minutes. Ra was forced to submit to Zhu Rong as his slave for the next millennium.
Since then, countless wagers had taken place and now Asiaq and Loki were sowing the seeds to be the next heavenly combatants.
"So we have a wager?" said Loki.
"Very well," agreed Asiaq, "although you will regret this. Your parlour tricks cannot compare the power of nature."
"We shall see." smiled Loki. "There's a lot more to me than you may think. I have won wagers with far greater gods than you my dear."
"Arrogance will be your downfall my friend."
Loki just smiled at her, "then shall we summon our referee?"
"If you really want to go through with this..."
"Then it's set." Confirmed Loki, "Apollo!!!"
In a flash Apollo appeared in the park. "So we have a wager?"
"Yes my friend, we do."