Some people try to explain that Jesus was born to a virgin because if he born like us he would become sinful. They then conclude that men are born sinful. I know that men are not born sinful. But I cannot able to explain to them the virgin birth of Jesus Christ. Please explain me the reason behind the virgin birth of Jesus Christ.
God has always provided hard evidence for the things He had taught. In the days of Isaiah, some 700 years before the Messiah was born, God revealed, "Therefore the Lord Himself will give you a sign: Behold, the virgin shall conceive and bear a Son, and shall call His name Immanuel" (Isaiah 7:14). A woman cannot bear a child without a father. This sign that God offered would be unique in the history of the world.
Notice that what your friends are doing is trying to add additional reasons for the birth beyond what God has said. There is no passage saying that sins are inherited; it says the opposite actually in Ezekiel 18:20. There is no passage saying that Jesus was born of a virgin to avoid inheriting sin. This is a case where people have decided what was to be, and then seek ways to explain away the objections.
Jesus had Mary as his mother and God as his father. Luke in chapter 3 shows that Jesus was a descendant of Adam; thus, the term "Son of Man" is an appropriate description of Jesus. Matthew points out the Jesus was Immanuel (Matthew 1:23); thus, the term "Son of God" is also an appropriate description of Jesus.