The qualfications for atoning for humanity's sin rest on the purity of the Deliverer; thus, the Deliverer is born of a virgin.

"Therefore the Lord Himself will give you a sign: Behold, a virgin will be with child and bear a son, and she will call His name Immanuel.” Isaiah 7:14

The Deliverer upon whom the Spirit rests will have no sin; otherwise, He wouldn’t be qualified to crush the head of the serpent, but would be under the serpent’s head. A sin-imprisoned man cannot set others free from sin. His qualifications for atoning for humanity’s sin will rest on the purity of His life. Therefore, the Deliverer is born of a virgin. The contaminated seed of Adam won’t be in Him. And when the virgin names Him she will recognize Him as the Promised One. She will call Him “God-With-Us,” Immanuel.