Yom Teruah (Day of Blowing [Trumpets]) has a number of nicknames, such as Rosh haShanah (New Year). Regardless of what you call it, Yom Teruah has a special purpose in God’s calendar. It’s a day of remembrance, a day of gathering, a day of awakening and a day of offerings. But mostly, it’s the Judgment Day. It’s a day when the wicked are judged and the righteous are vindicated by the Mashiakh (Messiah).
Apostles Paul and Yokhanan wrote a lot about this day, as did the prophets.