God’s calendar includes seven extra 30-day months in each 19-year cycle. This calendar rule, alone, ensures that birth dates would vary widely from year to year throughout one’s lifetime. It is as though the sacred calendar was designed by God to make birthday celebrations impossible to observe, while the Roman calendar was specifically designed to make celebrating birthdays more convenient.
The Restored Church of God (n.d). Are Birthday Celebrations Christian? Available http://rcg.org/articles/abcc.html. Last accessed 26th Jul 2014.