Hajj for Heathens Why Muslims go to Mecca Omar Chatriwala Every year—on exactly the same days, as far as Muslims are concerned—literally millions of people descend upon the original Mecca™ of Saudi Arabia and its surrounding holy sites in pilgrimage. Notable for infidels though, is that Muslims use a lunar calendar (based on the moon's cycle, like werewolves), which is about 11 days shorter than the standard Gregorian Calendar—so named for its 16th century patron Pope Gregory XIII (still wondering why Muslims don't use it?). Non-believers can thus be excused for thinking that Hajj falls on a different date each year. In 2010, things got under way in the holy land over the weekend.

Muslims arrive from all corners of the globe (they check the secret handshake, so no point trying to get in non-believers). Women wear what they please (don't they always?) while men don two towels, meant partly as as a way of levelling rich and poor (not so different from a locker room, smells included). Part of the challenge—and it is meant to be a challenge—is simply getting along with so many people from so many different backgrounds (that must've been hard for this guy).

DAY ONE: To kick the whole thing off, most pilgrims head to Mina—a sprawling tent city east of Mecca. They'll arrive at all times of day, spending the night there as a way point en route to the plain of Arafat. At this point, everyone's still in pretty high spirits.

DAY TWO: The Day of Arafat. Pilgrims head there in the morning, elbowing through throngs to stand on the plain, or amble up onto the relatively small Mount Arafat.

They'll spend the day in reflection and prayer (yep, a whole day!), asking for forgiveness for—in some cases—a lifetime of misdeeds. Others will likely commit new offenses as the crowds, heat and lack of personal hygiene begin to affect moods.

At sundown (technically the next day on the lunar calendar) pilgrims head back—stopping for the night to pick up pebbles at a spot called Muzdalifah. DAY THREE: Time to stone Satan—and celebrate. Its Eid day for Muslims around the world, which is as close to Christmas as we get. But instead of celebrating the birth of Jesus, this day is all about Abraham agreeing to sacrifice his son at God's behest.

That's the story anyway, and to re-enact it, pilgrims go to Mina to throw pebbles at giant stone walls representing the devil. That's what Abraham did when Iblis (Satan's Arabic name) tried to tell him killing his son wasn't a great idea. It was, in fact, a test of faith. And needless to say, when Abraham ignored the devilish appeal and went to do the deed, he found God had given him a sheep to slaughter instead. So Muslims celebrate with lots of meat—spread among family, friends and the poor.

Back at Hajj, pilgrims are undertaking what is historically one of the most dangerous rites. While everyone knows those symbolic columns they throw their pebbles at are not actually the Devil, some tend to get a little bit carried away (as Muslims do from time to time) and, like in 2006, people sometimes die in the crush. Saudi authorities though, have sought to rectify that by expanding the spot into a six-tier bridge—as of this year—that distributes the traffic.

With the stoning done, pilgrims sacrifice their animals and their hair—a buzz cut or a trim for guys, just a lock for women—and change back into their civvies. DAY FOUR-SIX: That's pretty much it. Pilgrims hang out in their tents in Mina for the next two-three days, going back to to give Satan a bit more "what for" each day.

At some point they'll head back to Mecca to perform elements of the "minor pilgrimage." That has two parts—circling the Kaaba (that black box, aka House of God) and hustling between the mountains of Safa and Marwa—another Abrahamic legacy we can get into another time. And then, well… they all head home. Bedecked in their finest Muslim garb, the millions once again board international airliners flying to the world's four corners—raising terror alerts from Brooklyn to Bangkok with the conclusion of their spiritual journey.