Here is Eve's testimony concerning the first child born to the human race. To understand it, we need to recall God's first promise: "I will put enmity between thee and the woman, and between thy seed and her seed; |He| shall bruise thy head, and thou shalt bruise his heel" (Genesis 3:15). These words, addressed to Satan, promised that the woman's "seed" would destroy Satan. Thus, that seed would have to be a man, but the only one capable of destroying Satan is God Himself. Eve mistakenly thought that Cain would fulfill this promise, and when he was born, she testified: "I have gotten a man--even the Lord" (literal rendering).
Over three millennia later, essentially the same promise was renewed to the "house of David," when the Lord said: "Behold, |the| virgin shall conceive, and bear a son, and shall call his name Immanuel" (Isaiah 7:13-14). The definite article reflects the primeval promise that the divine/human Savior, when He comes, would be born uniquely as the woman's seed, not of the father's seed like all other men. His very name, Immanuel, means "God with us" (Matthew 1:23). He is "the Word . . . made flesh" (John 1:14).
While questions have been raised about the precise meaning of almah (Hebrew word translated "virgin"), there is no question in the New Testament: "Behold, |the| virgin |Greek parthenos, meaning 'virgin' and nothing else| shall be with child" (Matthew 1:23). "When the fulness of the time was come, God sent forth His Son, made of a woman" (Galatians 4:4). "Forasmuch then as the children are partakers of flesh and blood, he also himself likewise took part of the same; that through death he might destroy him that had the power of death, that is, the devil" (Hebrews 2:14). HMM http://www.icr.org/article/5922/