Feasts dates should never be a point of contention or division. The point is to “Keep the Feasts”, for obedience is better than sacrifice (1 Samuel 15:22). So whether you keep the Feasts according to the Aviv or the Rabbinical Calendar, go out and keep the Mitzvot of keeping the Feasts.
ALL of our MOEDIM Dates (Appointed Times) are celebrated according to the BIBLICAL NEW MOON/ROSH CHODESH (the dark covered moon and not the crescent moon). The Biblical Calendar is a LUNI-SOLAR CALENDAR and not a Lunar or Solar Calendar; with DAYS and FEASTS beginning at SUNDOWN and with the first month of the Year starting in AVIV (NISSAN) in the Spring and not in TISHREI in the Fall. Our Rosh Chodesh Dates reflect our local area times which begin the Sundown closest to Lunation (others observe it the sundown before or after lunation or whichever lunation time is closest to sundown times). Please check your Local Times for Lunation and Sundown Times. Our Moedim & Feast Dates, reflect our Local Area dates.