But I am advocating for the Biblical Calendar, and I wanted to give you a little insight into how it works. It would not be at all suitable for commerce, but it is what Heavenly Father would prefer for us to use for spiritual purposes. No doubt about it! The Biblical Calendar is a 12 month calendar, and it always begins the year with the New Moon Day of Month 1 on the closest New Moon Day to the Spring Equinox. It has a 13th month every third year. When the year starts at this point, the events such as the barley harvest, all line up perfectly.