“Through [Jesus’] Resurrection Christians were begotten again to a living hope (I Pet. 3). The decisive statement of Paul in the account of his conversion in Gal. 1 is that it pleased God to reveal his son in him (v. 16). Conversely but to the same effect, if a man is in Christ he is a new creature (II Cor 5.17). Through him God has poured out the Spirit on us as “the bath of regeneration and renewal (Tit. 3.5). Nor is the meaning any different in other passages which speak of the new beginning and the birth of man from God. It is true exegesis, not eisegesis, to say that the nativity of Christ is the nativity of the Christian man; Christmas Day is the birthday of every Christian” (15).
A Christmas Comment from Barth (CD, IV/4)