I would go along with RexDart and Spavined Gelding and say that the agricultural revolution (and therefore, “civilization”) is pretty hard to top as far as significance to human history.
Nevermind that in the times in which you refered, christianity only impacted maybe… 10% of the populated world? If even…
I’ll go with Rexdart, Spavined Gelding and Diogenes the Cynic in saying that the agricultural revolution is the most signifigant event.
With it, we have permanent settlements, leading to cities, cultural identities, and so on.
If it’s a particular event, a moment in time, it’s hard to overlook the first few seconds of flight on December 17, 1903 in Kitty Hawk.
As long as we are talking about fictional events, I would say the time when Superman reversed the rotation of the Earth to go backwards in time.
Uh… Chumpsky, there was actually a person called Christ and he did die. The Romans kept meticulous records.
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I’d say the bringing of the Printing Press to Europe by Guttenburg.
Two points:
(1) There was never any such person named Jesus Christ. “Christ” means savior. The character that is proposed to have existed was named Jesus of Nazareth. He was called “Jesus the Christ,” as in “Jesus the savior, redeemer of Mankind.” That was all just made up stuff, though.
(2) Which Roman records?
So there was no person named Mahatma Gandhi? Just a Mohandas? Come on, is nitpicking the best you can do?
I’d have to look it up, but it is known by historians that the Romans chronicled an extrodinary amount of stuff. One thing, deaths of people.
Btw, as you are admiting that there was a Jesus of Nazareth, are you insinuating that he didn’t die? Does that mean you believe that he is still alive? 
And btw, I didn’t say there a person NAMED Christ, I said there was a person CALLED Christ, and there was.
Tell you what. You find those Roman records showing that Jesus of Nazareth actually existed, and I will convert to Christianity today. I’ll even let you pick the denomination.
It ain’t exactly Roman, but something to chew upon:
http://dsc.discovery.com/news/briefs/20021021/jesus.html
(I’m just waiting for you to denounce this as a conspiracy)
Oh, btw, I’m not a Christian, if that crossed your mind.
Part of the article (I can post parts of articles, right?), mentions:
Roman enough?
Oh please. A jewelry box made in the late 70’s C.E.?
I mean, it’s an interesting archelogical artifact, but it proves nothing. I want to see those Roman records!
I quoted it for you. The dedication tablet mentioning Pontius Pilate is Roman in orgin. That is a Roman record of Christ.
There are also testimonies by the guards that saw the crucifixition.
OK, you’ve convinced me that Pontius Pilate existed.
Jesus of Nazareth, on the other hand …
Hmmm, how about the work of the historian Josephus, who lived around the time Jesus was allegedly alive:
Actually, he was almost certainly called “Joshua bar-Joseph” in his time, “Jesus” being a Greek variant that was applied later. I’m an atheist, myself, but I have little doubt that such a man did exist, though much that has been written about him is highly dubious.
Personally, I think the most important event was the first formal written alphabet. The least important recent event was Chumpsky missing his afternoon nap and getting all cranky.
Do you have any quotes that haven’t been doctored?
(The quote attributed to Josephus is a well-known fabrication.)
Guys, impressive hijack.
Now stop it, mkay? Look, as far as I know, the best evidence, direct, we have, outside of the Gospels, which were written anywhere between 65 and 134 AD, http://www.straightdope.com/mailbag/mbible4.html ,
some sentences in Josephus, which may have been added by a later translator (No, I don’t have a cite for that, I keep finding it referenced as probable), as it is a long and laudatory note, while there is a much more probable mention a bit earlier about James being stoned, someone named Lucian of Samosata, and Suetonius, who wrote Life of Claudius.
http://www.christiancourier.com/archives/historicity_jesus.htm
although that may be “Continual rioting in the name of the rabble rouser Chrestus.”
As for the Ossuary, the bone repository, not a jewel box, it is possible the “Brother of Yeshua” part was added, but not yet completely certain. See the last page of this thread.
http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=140636&highlight=james+ossuary
This gentleman, thank you, Libertarian, seems to feel this is the most appropriate interpretation of the evidence.
http://www.concentric.net/~Mullerb/index.shtml
Here’s Cecil on the topic,
http://www.straightdope.com/classics/a2_275.html
So… Did he exist? As yet, unknown. We know more about him than we do about Alexander the Great, and possibly Socrates.
But until you make a time machine, I can’t be sure.
Oh, yes. My personal opinion? First, of course, creation. The spark that collapsed the dust cloud into the sun and planets. Second, life. Third, meteor impact. Fourth, Mankind. Fifth, speech. Sixth, domestication. Seventh, agriculture. (I feel that domestication had a more obvious impact that paved the way to agriculture… Animals are more obvious a choice to tame than plants, and the conceptual breakthrough is easier after), Eighth, Fire. The wheel is not on here. It is important, but not necessary. Fire is the ultimate example of man taking control of his environment. Ninth, writing. The fact that knowledge can be passed down properly from generation to generation or to unmet people is as much more powerful than speech is than speech is from lack of language.
Everything after that becomes pretty pale.
Except possibly Tenth… The Apollo Missions.