“Someone pointed out to me that the word ‘virgin’ in Isaiah 7:14 is the Hebrew word ‘almah’ meaning, ‘a young woman’—in other words, a ‘young woman’ who may or may not be a virgin. I am a firm believer in the virgin birth of Christ, but how do I address this dilemma?”
It is true the Hebrew word almah simply means a “damsel” or a “maiden,” who may or may not be a virgin. However, almah can refer to a young woman who is a virgin, such as in the case of Rebekah (Gen. 24:43-45). Interestingly, the Holy Spirit does not leave the matter open for debate in regard to Mary. Under the guidance of the Spirit, Matthew directly quotes Isaiah and, in doing so, he uses the Greek word parthenos. This term is solely used of a woman who has never known a man.
“Behold, a virgin [Gr. parthenos] shall be with child, and shall bring forth a son, and they shall call his name Emmanuel, which being interpreted is, God with us” (Matt. 1:23).
The purpose of the miraculous conception and virgin birth of Christ was to show that He was not stained with Adam’s sin. As Paul says, “He knew no sin” (II Cor. 5:21). Christ was an empty vessel when it came to sin. This allowed the Father to pour our iniquities into His dear Son at Calvary, where He was made “sin for us.” It is essentially a matter of faith! If Christ wasn’t born of the virgin, then we are yet in our sins. source