And that is why God provided Jesus with an earthly father. He wasn’t a bastard, He had a father. What illicit relationship? If God did not have sex with her, where is the illicit relationship?
Joseph was not his biological father. Jesus "father" contributed DNA and chromosones outside of marriage to Mary. That by definition is an illicit relationship constituting a bastard child. Think about it. You are a married woman. Some entity approaches you and tells you to bear a child outside of your marriage. You agree? and have the holy ghost make you pregnant. You are not married to that holy ghost. So the child is by definition a bastard child. So it doesnt take actual sex for the illicit relationship. Especially in those days...a woman showing up pregnant and blaming it on a holy ghost would have been a huge scandal. G-d would never put a human being through such a thing. Nor could he since G-d cant break his own moral laws.
Furthermore, Isaiah 7 was never about a virgin birth. It was about a child being born to a young woman who by the time he reached the age of maturity, two enemy kings would be dispatched. What good would a prophecy be to king Ahaz, that takes place 700 years in the future! And if Isaiah 7 was for a virging birth, it means that there were two virgin births since the prophecy was for king Ahaz in his day. The plain meaning of the text is that Isaiah 7 only pertained to Ahaz and the "sign" wasnt a virgin birth but the age of the child. Read it!