Luke 1:26-27
In the sixth month, the angel Gabriel was sent from
God to a town of Galilee called Nazareth, to a virgin
betrothed to a man named Joseph, of the house of
David, and the virgin's name was Mary.
Nicene Creed (325), Constantinopolitan Creed (381)
... Who for us men and because of our salvation came
down from heaven and was incarnate by the Holy Spirit
and the Virgin Mary and became human.
 
Catholic Christians and many other Christians also
believe that Mary remained a virgin for the rest of her life.
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Nicea
Constantinople