A New Calendar for Atheism

[theyear12013]

To understand the point about the calendar as a symbol of religious or cultural significance: here is a sample of active calendars in the world. Why do these cultures and religions sustain these calendars in the modern world? It isn't practical is it? So why are they doing it? Please engage the idea of the calendar systems being active even if they are not used by the state (though I don't know if China, Israel and Saudi Arabia incorporate them into the state or not?)

Holocene calendar 12013

Gregorian calendar 2013
Assyrian calendar 6763
Buddhist calendar 2557
Chinese calendar 壬辰年 (Water Dragon)
4709 or 4649
4710 or 4650
Hebrew calendar 5773–5774
Hindu calendars
- Vikram Samvat 2069–2070
- Shaka Samvat 1935–1936
- Kali Yuga 5114–5115
Iranian calendar 1391–1392
Islamic calendar 1434–1435
Korean calendar 4346
Thai solar calendar 2556

http://en.wikipedia.org/wiki/Gregorian_calendar