Luke 1:30-35 Then the angel said to her, “Do not be afraid, Mary, for you have found favor with God. And behold, you will conceive in your womb and bring forth a Son, and shall call His name JESUS. He will be great, and will be called the Son of the Highest; and the Lord God will give Him the throne of His father David. And He will reign over the house of Jacob forever, and of His kingdom there will be no end.”
Then Mary said to the angel, “How can this be, since I do not know a man?”
And the angel answered and said to her, “The Holy Spirit will come upon you, and the power of the Highest will overshadow you; therefore, also, that Holy One who is to be born will be called the Son of God.
19.16 And make mention of Mary in the Scripture, when she had withdrawn from her people to a chamber looking East,
19.17 And had chosen seclusion from them. Then We sent unto her Our Spirit and it assumed for her the likeness of a perfect man.
19.18 She said: Lo! I seek refuge in the Beneficent One from thee, if thou art God- fearing.
19.19 He said: I am only a messenger of thy Lord, that I may bestow on thee a faultless son.
19.20 She said: How can I have a son when no mortal hath touched me, neither have I been unchaste?
19.21 He said: So (it will be). Thy Lord saith: It is easy for Me. And (it will be) that We may make of him a revelation for mankind and a mercy from Us, and it is a thing ordained.
The Bible and Quran both say Mary was a virgin, untouched by man. The Quran calls the birth of Jesus "a mercy from Us" [God]. What could be more merciful than providing a method of redemption from our sins?
The prophet Isaiah said a virgin will conceive - the Quran says Mary was a virgin. Isaiah said this son's name will be Immanuel, which Matthew says means "God with Us!"
Ask your Muslim friend if there was another virgin who conceived and bore a son. No? Then Isaiah must be talking about Jesus, the same Jesus in Sura 19, born of a virgin according to the Quran, who is a mercy from God, and is in fact GOD WITH US!