Jesus Christ without any doubt has by far the most influence in history of mankind. No one before Him had and no one after Him would have an impact that will even come close to His. Even history itself is divided before and after Him: History before Christ (BC) and History after Christ (AD, Anno Domni, year of the Lord), this is power beyond belief, power that no other person would ever have.
Christ was downgraded, because it was a team effort with St. Paul, who was ranked 4th I think (the message plus the messenger). Neither would have had much influence without the other is the theory. Mohammed was ranked first because he was a twofer. He rewrote the map in a secular sense as a conquerer, as well as single handedly found the second most influential religion on the planet. You will never guess who was ranked fifth, assuming my recollection is correct. :)