My argument is based on my conclusion that you can not wholly refute the title of "World Champion". I start by crowning a champion as a "World Champion" and then ask the question "Is there anyone who is talented enough to challenge?" In the case of the NFL and American football, there is no one team outside of the NFL who is talented enough to challenge. The NFL is the premier professional American football league and anything is else #2 at best. Therefore, the NFL champion is the "World Champion". When you get into baseball or basketball, you need establish that MLB and the NBA are the premier professional leagues for their respective sports because there are high level professional leagues around the world. You would do this by asserting that the world's most talented baseball and basketball players come to MLB and NBA after they've reached the pinnacle of their own home country's league. The simple way for me to explain why the rest of the international community rejects the idea of an NFL champion being a "World Champ" is this: But that is just impossible to prove. Being an American who posts at this site, I've seen more than one occasion of blind American hate and I haven't even been here that long so I know it's there. People hate America and just assume we are arrogant for crowning our league champs as "World Champs". Edit: Famine beat me to the punch.