It is obvious from the above that the historical question whether the church of the apostolic age knew and practiced infant baptism must be answered in the affirmative with a very high degree of probability. But that fact in no wise decides the theological question concerning the right of infant baptism. After all, the church of Corinth in the days of the apostle Paul practiced a vicarious baptism for the dead [I Corinthians 15:29]. It is possible, therefore, that we are dealing here with a very ancient abuse. Theologically, infant baptism can be grounded only on Scriptural evidence which proves it to be a legitimate form of Baptism.
The argument against infant baptism formerly raised by the Anabaptists and today by Karl Barth is that the essence of the Sacrament of Baptism includes "the responsible willingness and readiness of the person to be baptized" to receive the divine promise and to accept the divine obligation (Barth, op. cit., 23). In an essay in the Berlin religious weekly Die Kirche some time ago, a disciple of Barth attempted to prove the correctness of this view by a reference to the story of the Ethiopian Eunuch (Acts 8) where, as he maintained, not only an expression of the will of the candidate preceded his baptism but also his confession of faith as a condition for receiving it. Unfortunately, that theologian had overlooked the fact that verse 37 with its solicitation of a confession of faith and the making of that confession is an ancient addition to the original text, as is shown by a study of the manuscripts. The oldest and best manuscripts do not have it and thus confirm the fact that in the primitive church (cf. Acts 2:41) Baptism was sometimes administered without a spoken Credo.
So the question is: What is Baptism according to the testimony of the New Testament? What does it give or profit? What is the relation of Baptism to the faith of the baptismal candidate? Is it necessary for salvation or not? Our first answer must be that, according to the clear teaching of the New Testament, Baptism is "the washing of regeneration." The ancient church, which always actually identified Baptism and regeneration, and the church of all times with the exception of the Reformed denominations, has understood Titus 3:5 in this sense, and rightly so. There Baptism is said to be "the washing of regeneration and renewing of the Holy Ghost."
In Baptism the Holy Spirit is communicated; we are "all baptized into the one body" (1 Corinthians 12:13). Those who are baptized have been baptized into Christ's death (Romans 6:3). These are all realities that take place, not alongside of Baptism, but in Baptism. In the New Testament, Baptism with water, inasmuch as it is a baptism into Christ, into the name of Christ, is Baptism with the Spirit, it is a being born anew and at the same time from above "of water and of the Spirit" (John 3:5). Certainly the New Testament knows of no regeneration without Baptism and independent of Baptism. Baptism, therefore, is not a sign but a means of regeneration. To take it only as a sign of a regeneration, that also takes place without it and independently of it, is unbiblical.
The Reformed Church in its doctrine of Baptism, precisely as in its doctrine of the Lord's Supper, on the one hand rejects the pure symbolism of Zwingli, as though Baptism were nothing but an "ostensible" sign of the Christian profession like the white cross which the confederate attaches to his garment in order to show that he is a confederate; but on the other hand it also rejects both the opus operatum of the Roman sacramental doctrine and the Lutheran and New Testament identification of sign and substance.
Why does it do this? In the final analysis, it is because of the aversion of Calvin and his medieval theological predecessors to the view that an external, physical act can evoke spiritual effects like the forgiveness of sins. But this is, in the first place, a philosophical prejudice, and in the second place it is a misunderstanding of the significance of the Word of God in Baptism. "For without the Word of God the water is simply water and no Baptism; but with the Word of God it is a Baptism, that is, a gracious water of life and a washing of regeneration." Even in Catholic doctrine the Word as forma is inseparably united with the sacrament; as Augustine's famous dictum, quoted over and over again by all occidental churches, puts it: Accedit verbum ad elementum et fit sacramentum [The word comes to the element and it becomes a sacrament; Tractate 80 on John 3; Smalcald Articles III.V.1].
That which separates Luther from the Catholic doctrine of Baptism is best stated in his own words in the Smalcald Articles, where he draws the line between himself and Thomism as well as Scotism at the same time:
Therefore we do not hold with Thomas and the monastic preachers or Dominicans, who forget the Word and say that God has imparted to the water a spiritual power which, through the water, washes away sin. Nor do we agree with Scotus and the Barefoot Monks who teach that by the assistance of the divine will Baptism washes away sins, and that this ablution occurs only through the will of God and by no means through the Word and water. (SA III,V 2-3)
For Luther, everything depends on the close connection of water and the Word:
But that this presence of God or Christ cannot be any other presence than that in his Word will not need to be proved, we trust, in the case of Luther. All effects of Baptism, in the view of Luther and the Lutheran Church, are effects brought about by the Word connected with the water.
Consequently, the Reformed objection to the Lutheran interpretation of Baptism is none other than the objection to the Lutheran doctrine of the means of grace in general. That God gives his Spirit—and with him forgiveness of sin, life and salvation—to no one without the external means of his grace, without the external Word, without Baptism, without the Lord's Supper: that is the point against which this objection is directed. "The power of Jesus Christ, which is the only power of Baptism, is not bound to the execution of Baptism" (Barth, op. cit., 14f.). A favorite distinction made by the older Reformed theologians was the one between external baptism by water and internal baptism by the Holy Spirit and the blood of Jesus Christ, which cleanses us from all sin. The reception of both, they said, does not always coincide; it is possible to have the one without the other. Whether an individual receives the Spirit-and-blood baptism together with the water baptism depends upon whether he is one of the predestined or not. This point of view also accounts for the objection to emergency baptism, which has been raised again and again since Calvin, especially against the Weibertaufe (baptism by women, midwives). Even so late a document as the Union Constitution of the Palatinate contains the sentence: "The Protestant Evangelical Christian Church of the Palatinate does not recognize emergency baptism" (E. F. K. Mueller, Die Bekenntnisschriften der Ev.-Reformierten Kirche, 1903, 871).
After all (they say) Baptism cannot give man anything he would not have without Baptism. Salvation and damnation do not in any sense depend upon Baptism, but only upon the question whether a man has been predestinated unto salvation or not. That is classic Reformed doctrine. And even where, as in the school of Barth, the old predestination doctrine has been softened up or surrendered, the conclusion still stands: Baptism has been instituted by Christ—Calvin agrees with Luther and the universal tradition of the Eastern and Western churches that the institution is identical with the baptism of Jesus—hence it must also be practiced as an ordinance of Christ, but it is not necessary for salvation. According to Karl Barth (op. cit., 15), one can only speak of a necessitas praecepti [necessity of command], never of a necessitas medii [necessity of means].
 "Andrea [at Montbeliard] argued that external baptism is accompanied by interior regeneration and the gift of faith. Beza said that what happens interiorly is known only to God and may not be presumed because of human [sic!] actions." Raitt, The Colloquy of Montbeliard, p. 147. MH