Ptolemy I Soter was succeeded by his son, Ptolemy II Philadelphus. By the time Philadelphus took the throne, the Jews in Alexandria spoke Greek rather than Hebrew.
Because there was a need for a Greek translation of the Holy Scriptures of Judaism, Ptolemy II commissioned 70 Palestinian Jews to translate the Hebrew Scriptures into Greek in the third century BC. In recognition of their work, the translation was dubbed the Septuagint (from the Latin, septuaginta, meaning seventy).
Among the books translated by the Hebrew scholars was the book of Isaiah. The most controversial passage translated by the sages was Isaiah 7:14. The English translation of the Greek reads as follows: Therefore the Lord Himself shall give you a sign; Behold, the virgin shall conceive, and bear a son, and shall call His name Immanuel.
Now the Hebrew word in question is “almah” which means a young woman (who is not necessarily a virgin). However the scholarly Jews commissioned by Ptolemy saw fit to translate “ha’almah” into the Greek “ha parthenos” which literally means “the virgin.”
The sages not only translated the phrase but also made an interpretation based on its context. “What kind of sign, then, would that have been—a young woman who was not a virgin giving birth to a child? And which of the two is more appropriate as the mother of Immanuel, a woman who has had intercourse with a man and has conceived after the manner of women or one who is still a pure and holy virgin? Surely only the latter could produce a being at whose birth it is said, ‘God with us.’”
Jesus Christ was the embodiment of the eternally begotten Son of God. It is fitting that He did not have a biological father. Instead, Mary conceived after being overshadowed by the power of the Holy Spirit. It is also appropriate that Jesus was born into the family of Joseph of Nazareth. Joseph was a descendant of King David the Bethlehemite, a man after God’s own heart.
The LXX was in popular use at the beginning of the Christian era. Scholars believe that most of the Old Testament quotations found in the New Testament are based on the Greek Septuagint as opposed to the Hebrew version of the Holy Scriptures of Judaism.