You don't have to die to keep the John Doe idea alive. Someone already died for that once. The first John Doe.
9 seconds sound clip from the Meet John Doe (1941) movie soundboard.
You can hear this line at 01:59:54 in the DVD version of the movie.
Quote context
[...]
- John, if it's worth dying for, it's worth living for.
- Please! Please God, help me!
- You want to be honest, don't you?
- And he's kept that idea alive for nearly 2000 years.
- It was he who kept it alive and he'll go on keeping it alive forever and always.
- For every John Doe movement these men kill, a new one will be born.
[...]