What you understand with Isaiah 7:14 14 Therefore the Lord himself shall give you a sign.?

It means what Luke's account says it means. Compare Mt. 1:20-25.

the idea of a virgin and a young maiden is a dispute between what christians teach today and what modern rabbis teach. the bible old testament itself uses the word virgin and young maiden in the same context. aiui. the rabbi will say that the term young maid is more correct to describe whom Isaiah is talking about. however, it is possible to conceive without sexual intercourse if there is a practice of invitro-fertilization.

The sign was a Virgin bearing a Son - the Lord Jesus Christ whose Father was GOD ALMIGHTY. Jesus was the SIGN - Israel's MESSIAH.  Israel's King of the Jews.  Mary was married to Joseph and as a normal Jewish wife, after Jesus was born of God and not Joseph, Mary bore children to her Husband. Those children's father was Joseph.  Joseph was NOT Jesus' Father - God was.

Original text said maiden, not virgin.

Isaiah 7:14 is nothing to do with Jesus. 

Almah means young woman. 

Immanuel means god is with us.

The prophecy was to Ahaz, king of Judah, in that the kings enemies shall be defeated before the young woman’s child, Immanuel, is weaned.

She was a virgin at the time she became pregnant with Jesus due to the power of Jehovah God's holy spirit/power. (Luke 1:34 & 35) After she married Joseph, they later had more children and she was no longer a virgin at that point. 

Lots of impossible stuff happens in myths....

Read the whole chapter in context, it's not about Jesus.

SHE was a virgin till after Jesus was born and then she had other kids..

The fact of the matter: That verse is talking about God The Lord Jesus Christ our Lord and Savior. Who is the Lamb of God that is to take away the sins of the world. Emmanuel means God with us.