We spoke earlier about why the virgin birth is necessary to believe but not particularly theologically necessary. You can read it here.
The best arguments for the virgin birth are not that it is in some sense necessary or that it is required by any other doctrines but that it is theologically fitting. And it’s fitting in 4 ways:
1) It signals that something special and unique is occurring. This isn’t the birth of anyone ordinary, and it isn’t a miraculous birth of someone special, it is a whole different category of special person that is being born. The Bible has other miraculous births, Samuel in the Old Testament, John the Baptist in the New Testament. But Jesus’ birth is different and unique again from those miraculous births. Jesus is born of a real human mother, he is born just as every other human is, and yet he’s born in a unique way that corresponds to his unique person.
2) It’s more fitting in the sense that it places the spotlight on the filial relationship of the divine persons Father and Son. Jesus’ humanity is anhypostatic in itself, it has no independent personhood. The humanity of Jesus is personalised, it in enhypostasised in the person of the Word. And so it is fitting that the filial relationship not be between divine Son and human Father and divine Father. There’s nothing theologically wrong with that, it’s just more fitting that with the virgin birth the focus is on the relationship between God the Father and the person of God the Son in flesh.
3) The virgin birth fits theologically with the empty tomb, or as Torrance puts it “the empty womb links with the empty tomb. That is, in both the resurrection and the virgin conception we have a new creative act on the part of God. But it’s a new creative act within and out of the present created order. So the virgin birth is not an entirely new act of creation but instead a recreation within our human existence. There is continuity and there is discontinuity. And so in the resurrection we have a new creative act within and out of the present created order, not a completely new creative act but rather a recreation within our human existence. Continuity and discontinuity. And so the virgin birth and the empty tomb create something of a closed circle of revelation where each informs the other. But a virgin birth isn’t theologically necessary for a resurrection. Though it is theologically fitting, and it is reveals something about the significance of the resurrection, and vice versa.
And 4) the virgin birth is a doctrine that shows that the movement of the Son of God to become human is one directional, from God to man. And so the virgin birth removes synergism; God and man are not co-equal partners. The birth is grounded in the sovereign will of God alone. Not that it means that it’s an act of God without humanity. Humanity is of course fully involved, but God is the subject of the whole thing and man is the predicate. The virgin birth is an event that breaks into our human processes and is not a product of them.
And so the virgin birth is theologically fitting, even if it’s not theologically necessary or required.