From Quora:
The answer will shock you. It shocked me when I first studied movie history.
First of all, the most viewed film is not Avatar (2009) or Titanic (1997). Those two films set the box office record for “highest grossing film worldwide”—but highest grossing does not mean most viewed.
The average movie ticket price today is at least 10x more expensive than what is was in the past. And Avatar being a 3D movie, charged even more per ticket. So it’s very likely that Avatar’s viewership (in theaters) is at least 10x less than a top-performing movie from ten or more years ago.
So then, if we adjust the box office numbers for inflation, is the most viewed movie of all time Gone With The Wind (1939) ?
After all, more people bought tickets to see this movie in a theater than any other film ever, so do we have a clear winner? No.
A theater is not the only place you can watch a film. In 1977, VHS came to town, allowing people to watch and rewatch films in the comfort of their own homes.
Guess what other film came out in 1977? Star Wars Episode IV: A New Hope. Star Wars is the second highest grossing film of all time when adjusting for inflation, and not only that, this film has been released on VHS, then LaserDisc, then re-released in 1997 in theaters, and then re-released on DVD, and Bluray.
Every May 4, millions of people rewatch Star Wars. Every time a new Star Wars movie is released, millions of people have viewing parties. Star Wars is also probably the most pirated film of all time.
So do we finally have a winner? Close, but no.
The real winner is . . . Jesus (1979).
When the film was first released, (distributed by Warner Bros), it was a total flop. It lost $2-million at the box office. But God (or Campus Crusade for Christ) had other plans.
Remember what I said about the VHS? In 1981, Bill Bright, founder of Campus Crusade for Christ, created the Jesus Film Project. His organization translated the film to Tagalog and then released it on VHS. Since then, the organization translated the film to what is now 1600 languages and distributed the VHS to billions of people. No other film even has 1000 translations.
And no other film has been smuggled into countries as much as this one. Millions of Chinese (through the Cultural Revolution), Cubans, and even North Koreans have seen this film.
Not only that, the film has been distributed for free to people’s homes throughout the world.
I even received a copy for free. The VHS was in my mailbox one day in 2002, and I watched it. And I also remember viewing parties for this film happening in many different churches in my community (I lived in South Carolina at the time). Viewing parties are still happening today worldwide, and the film is shown somewhere on TV every Christmas.
New York Times, in 2004, estimated that at least 3-Billion people have seen the film. Since then, the film received an HD makeover and was re-released on DVD and Bluray in 2014.
It is also on Youtube, for free, and no one takes it down because the makers of the film just want people to see it. Many people.