Was treated fairly leniently and:
“There is no recorded incident where a non-Muslim was executed for entering restricted space in Madinah or Makkah”
Sir Richard Francis Burton famously posed as a Muslim doctor, and made the Hajj. His book about it, A Personal Narrative of a Pilgrimage to Mecca and al-Medina, is a classic, and I’ve read it several times. The appendices at the end give quotations from other non-Muslims who went there, generally against their will, as slaves. Burton knew that what he was doing was against Muslim law, and I have a feeling they wouldn’t have been so lenient if they’d caught him. Burton was a master linguist and actor, and could pass himself off as Muslim. He even recommended that other non-Muslims try the experiment.
If you want to know what it’s like, you can read Burton’s book, but it’s over a century and a half out of date. Or you can watch Spike Lee’s X, which has scenes in Mecca (filmed by a Muslim crew). Or National Geographic has a DVD about the Hajj, also made by a Muslim crew. One of the people they follow is an American woman who converted. I’m surprised at the number of people who asked her i she was Muslim. Certainly most of them must know that she would have to be, but I get the distinct impression that some of them don’t, wjhich is surprising.
I have never been to Saudi Arabia, though I converted to Islam when I got married. My wife and I have often discussed making the Hajj but it seems to us like it would just be a zoo. My understanding is that Saudi Arabia tightly restricts the movements of non-Muslims within the country, and that to even get a tourist visa you have to be part of an approved organized tour group with an approved itinerary. I do not know the process that Muslims must follow to get to Mecca, especially if they are from a Western country.
If you convert (and it is not a demanding process), you would be issued a certificate and most likely you would be all set. However, I do not know what security exists and what measures they might take to ensure you’re a Muslim. I would expect that if you don’t speak any Arabic that would arouse suspicion (there are certainly lots of non-Arab Muslims but the devout folks generally know Arabic from studying the Koran).
Traveling in Egypt, where my wife is from, we always make sure to bring my certificate and our Arabic marriage certificate for things like staying in hotels (even in relatively liberal Egypt many hotels frown on non-marital cohabitation) although after the kids were born they quit asking.
As noted in the article linked above, there are separate visas for Muslims and non-Muslims. So assuming you could convince the officer issuing the visa that you were a Muslim, you’d be good to go.
Well, according to the article on the 1979 Grand Mosque Seizue, some members of the French GIGN may have entered Mecca for an anti-terrorist operation, after receiving a quicky conversion to Islam. I don’t know how formal it was.
I’m taking it wouldn’t be pleasant