Isaiah 7:14

Isaiah 7:14

Therefore the Lord himself shall give you a sign; Behold, a virgin (5959 almah: a lass (veiled or private: damsel) shall conceive, and bear a son, and shall call his name Immanuel.

Matthew 1:23

Behold, a virgin (3933 parthenos: maidenhood, virginity; by implication an unmarried daughter: virgin) shall be with child, and shall bring forth a son, and they shall call his name Emmanuel, which being interpreted is, God with us.

Luke wrote that Mary, when told she was going to conceive, reacted to the announcement with a question "How can this be I have not known a man."

Mary testifying she was virgin does not require every occurrence of the word translated "virgin" to reference Mary. Nor does it require every mention of a young girl with high moral standards to refer to Mary.