The FIFA president believes the Barcelona and Real Madrid superstars have totally different styles, adding it is "wonderful" to have two such players in the game today.
The Barcelona and Real Madrid stars have been at the center of a debate over who is the world's best player for a number of years, and the head of the sport's governing body beileves the competition is a great asset to the modern game.
Speaking after delivering a lecture in Geneva, the 76-year-old Blatter told reporters, "We face two men with a different game and perhaps contrasting personalities. This is a good thing for football. I find it something tremendous.
"This struggle to determine who is the best in the world and who is second is something that we also have to see in football. Football cannot have one type of player. Imagine there were two like Messi or two like Ronaldo. It would not work well. They are polar opposites and I believe it is tremendous for football to have personalities like them."
Both Messi and Ronaldo are favorites for this year's Ballon d'Or prize, a title that the Portuguese star won back in 2008 but has been held by the Argentine maestro for the last three years.
Blatter explained that FIFA does not have final say on who is given the award, but that national federations are the ones responsible for voting.
"FIFA (does) not choose who is best. It is not us who decides," Blatter said. "It is the federations that have the election and the president has neither the right to veto, nor the right to vote. It's something sporting."