[Fai Mao]

And except I do not remember Christians killing each other over this difference.

[jmcenanly]

We simply fixed our calendar, going from Julian to Gregorian.

[mountainbunny]

And except I do not remember Christians killing each other over this difference.

Why would you say that? As if Christians haven't killed over the smallest things? When people are killed for ideas and faith, not actions, does the minutia of why matter?

I have no idea if Christians have killed over this specific issue, but they've killed over plenty of others. See: The Inquisition. The killing lasted from the 12th through 19th centuries. Christians and others were killed.

See also: English Reformation, Guy Fawkes, etc.

I'm a practicing Catholic. Pretending that Christians haven't killed over religion is dangerous and wicked. Don't pretend you're better. Know the past and don't deny it so that it is never repeated.