The Virgin Birth: an Essential of the Gospel of Christ
Many people who call themselves Christians do not believe in the essentials of the Gospel of the Christ. What is this gospel? Paul defines it for us:
Now I would remind you, brothers, of the gospel I preached to you, which you received, in which you stand, and by which you are being saved, if you hold fast to the word I preached to youâ€”unless you believed in vain. For I delivered to you as of first importance what I also received: that Christ died for our sins in accordance with the Scriptures, that he was buried, that he was raised on the third day in accordance with the ScripturesÂ (1 Cor 15:1-4).
Here, Paul says that the gospel consists of the atoning death and resurrection of Christ. But within these two historical events, are two others: the virgin birth and perfect life of Jesus. For without these other two, there will be no atoning death and resurrection.
This is explained clearly and succinctly in the Heidelberg Catechism Q&A 12-18 (with Scripture proofs). Question 12 says that God’s righteous wrath against man’s sin demands satisfaction:
Question 12. Since, then, by the righteous judgment of God we deserve temporal and eternal punishment, how may we escape this punishment and be again received into favor?
Answer. God wills that His justice be satisfied; therefore, we must make full satisfaction to that justice, either by ourselves or by another.
 Ex 20:5, 23:7; Rom 2:1-11;  Isa 53:11; Rom 8:3-4
Questions 13-14 then asks if anyone or any other creature can make satisfaction for his own sin. And the answer is no.
Question 13. Can we ourselves make this satisfaction?
Answer. Certainly not; on the contrary, we daily increase our guilt.
 Job 9:2-3, 15:15-16; Ps 130:3; Mt 6:12, 16:26; Rom 2:4-5
Q 14. Can any mere creature make satisfaction for us?
A. None; for first, God will not punish any other creature for the sin which man committed; and further, no mere creature can sustain the burden of Godâ€™s eternal wrath against sin and redeem others from it.
 Ezek 18:4, 20; Heb 2:14-18;  Ps 130:3; Nah 1:6
Question 15 then asks, if no man or any other creature can satisfy the righteous judgment of God,
Question 15. What kind of mediator and redeemer, then, must we seek?
Answer. One who is a true and righteous man, and yet more powerful than all creatures, that is, one who is also true God.
 1 Cor 15:21-22, 25-26; Heb 2:17;  Isa 53:11; Jer 13:16; 2 Cor 5:21; Heb 7:26;  Isa 7:14, 9:6; Jer 23:6; Jn 1:1; Rom 8:3-4; Heb 7:15-16
Without the virgin birth, Jesus Christ cannot be a true man and true God.
Questions 16-17 then explains why must this Mediator and Redeemer be a true man and true God:
Question 16. Why must He be a true and righteous man?
Answer. Because the justice of God requires that the same human nature which has sinned should make satisfaction for sin; but one who is himself a sinner cannot satisfy for others.
 Rom 5:12, 15; 1 Cor 15:21; Heb 2:14-16;  Isa 53:3-5; Heb 7:26-27; 1 Pt 3:18
Question 17. Why must He also be true God?
Answer. That by the power of His Godhead He might bear in His manhood the burden of Godâ€™s wrath, and so obtain for and restore to us righteousness and life.
 Isa 9:5;  Dt 4:24; Isa 53:8; Ps 130:3; Nah 1:6; Acts 2:24;  Jn 3:16; Acts 20:28;  Isa 53:5, 11; 2 Cor 5:21; 1 Jn 1:2
Finally, Question 18 reveals who this True Man and True God is:
Question 18. But who now is that Mediator, who in one person is true God and also a true and righteous man?
Answer. Our Lord Jesus Christ, who is freely given unto us for complete redemption and righteousness.
 Mt 1:21-23; Lk 2:11; 1 Tim 2:5, 3:16;  Acts 4:12; 1 Cor 1:30
If you reject the Virgin Birth of Christ, then the perfect life, atoning death, and glorious resurrection fall by the wayside. You have rejected the true Christian gospel.
Therefore, those who call themselves Christians but do not believe in the Virgin Birth, Perfect Life, Atoning Death, and Glorious Resurrection of Jesus Christ are not Christians. They are lost.