The Church celebrates the Nativity of St. John the Baptist and Forerunner today, on June 24.
According to the Orthodox tradition, the nativity of the saints is celebrated on the day of their dormition, because this day is the day of their depart in heaven. So, they are born in the Kingdom of Heaven. An exception is only the Nativity of Jesus, of the Virgin Mary, and of Saint John the Baptist. This is due to the fact that their birth is a link in the chain of the divine economy (i.e. the philanthropy of God) for the salvation of the world.
Saint John was miraculously born to elderly parents, the priest Zechariah and Elizabeth, who were without children.
His birth, as well as the name of the infant, was announced to Zechariah by an angel while he was in the temple. As recounted in Luke 1:39–57, at the Visitation of the Blessed Virgin Mary to his mother Elizabeth, John, sensing the presence of his Jesus, upon the arrival of Mary, leaped in the womb of his mother.
As St. Theodore the Studite mentions the birth of the Saint John the Baptist, “All these prophets of the Old Testament who came before Saint John do not reach his greatness. Because some of them lived before the written Law and others after it.
John, however, the son of the priest Zechariah and Elizabeth, was born and thrived in the interval between the Law and Grace. Saint John announced Jesus’ coming and prepared the people for Jesus’ ministry. There were many prophets who also prophesied or performed wonders. But the Precious Forerunner turned out to be a miracle worker while he was still in his mother’s womb.”
Source: Church of Cyprus