It was the standard calendar known for the world until 1582, when Pope Gregory created a new calendar, designed to correct the loss of days in the Julian Calendar.
Up until the 1920's all the Orthodox world chose to maintain the Julian Calendar for marking the holy days of the Church year.
Today, there is a 13-day difference between the two calendars.
BIRTH CONTROL: Though opinions vary among Orthodox on this issue, the view of most Orthodox bodies is that controlling conception through "natural family planning", or contraception, is acceptable for married couples, as long as it is done in a spirit of responsible Christian stewardship of life.
This means, first, that birth control will not be used merely because having and rearing children is seen as a financial or social inconvenience.
BODILY INTEGRITY: Orthodoxy holds the Biblical view that the body is the temple of the Holy Spirit.
As such, it must be treated with honour and dignity.
Secondly, it means that any form of contraception used will not be physically harmful to either spouse, and will not involve the abortion of a fertilized egg.
Finally, the decision to utilize birth control, as well as the decision to have a child, must be a mutual one between both wife and husband.
CHILIASM: Chiliasm, from the Greek word meaning "1000," is a belief based on Revelation 20:2-7.