From J. Gresham Machen’s classic work, The Virgin Birth of Christ (1930):
What, then, is our conclusion? Is belief in the virgin birth necessary to every man if he is to be a believer in the Lord Jesus Christ? The question is wrongly put when it is put in that way. Who can tell exactly how much knowledge of the facts about Christ is necessary if a man is to have saving faith? None but God can tell. Some knowledge is certainly required, but exactly how much is required we cannot say. “Lord, I believe; help thou mine unbelief,” said a man in the Gospels who was saved. So today there are many men of little faith, many who are troubled by the voices that are heard on all sides. It is very hard to be a Christian in these times; and there is One who knows that it is hard. What right have we to say that full knowledge and full conviction are necessary before a man can put his trust in the crucified and risen Lord? What right have we to say that no man can be saved before he has come to full conviction regarding the stupendous miracle narrated in the first chapters of Matthew and Luke? We desire, however, at this point not to be misunderstood. We do not mean by what we have just said that denial of the virgin birth is to be treated as a matter of indifference … A man is not saved by good works, but by faith; and saving faith is acceptance of Jesus Christ ‘as he is offered to us in the gospel.’ Part of that gospel in which Jesus is offered to our souls is the blessed story of the miracle in the virgin’s womb. One thing at least is clear: even if the belief in the virgin birth is not necessary to every Christian, it is certainly necessary to Christianity.