In order that there may be a valid baptism, there must be application of water to an individual; for water and its application are essential elements of this sacred ordinance. But water alone does not make Baptism a Sacrament. As Luther rightly says in his Catechism: "Baptism is not simple water only, but it is the water comprehended in God's command and connected with God's word." St. Augustine expresses the same truth in the words: "When the Word is connected with the element, then the act becomes a Sacrament" (Accedit Verbum ad elementum et fit sacramentum); that is to say, the act becomes a Sacrament when it is performed according to Christ's institution. While the application of water is important, it is really the word of Christ connected with the application that makes Baptism "a washing of regeneration and renewing of the Holy Ghost."
The nature of this word of Christ is twofold. In the first place, it is a command (Matt. 28, 19 lit.: "Going therefore, disciple all the nations make disciples of all the nations, baptizing them"). As the apostles were to go, so they were to make disciples by baptizing. The command to baptize is therefore very clear.
In the second place, the divine word connected with Baptism is a promise (Matt. 28, 19: "into the name {εἰς τὸ ὄνομα} of the Father and of the Son and of the Holy Ghost"). What these words express is that Baptism is not an empty ceremony, but an efficacious means of grace, by which the baptized enters (through faith, of course, and not merely ex opere operata) into communion with the Triune God. The words therefore are a most gracious promise and as such explain why the apostles could "make disciples by baptizing."
The baptismal promise is stated more clearly in Ma.rk 16, 16 as follows: "He that believeth and is baptized shall be saved." In Rom. 6, 4 the promise is put still more definitely: "We are buried with Christ by Baptism into death" (sc. Christ's death). In Gal. 8, 27 St. Paul declares that they who have been baptized into Christ have put on Christ, namely, His righteousness and merits (justification).
Baptism is therefore correctly defined as water comprehended in God's command and connected with God's promise of forgiveness of sins, life, and salvation.
It has been pointed out (Tertullian, De Bapt., c. 5) that some heathen religions had their own established baptisms (Sacris quibusdam nationes exterae per lavacrum initiantur Isidis alicuius aut Mithrae). These baptisms were man-made and therefore inefficacious; but Christ, the omnipotent, omniscient Lord, established by His divine command that true Baptism (a divine means of grace) through which the baptized enters into communion with the true God and all His spiritual blessings of grace and forgiveness "(καθαρισμός, λουτρόν παλιγγενεσίας καὶ ἀνακαινώσεως πνεύματος ἁγίου, Titus 3, 5 f.).
Since Christ commanded His holy apostles and thus the entire Christian Church to baptize "in the name of the Father and of the Son and of the Holy Ghost," this form of Baptism (Tauf-formel) must be employed by the Christian believers whenever they administer the holy Sacrament. This is not disproved by the fact that Scripture sometimes speaks of Baptism as performed "in" or "into the name of Christ" (Acts 2, 38: ἐπὶ τῷ ὀνόματι Ἰησοῦ Χριστού; 8, 16: εἰς τὸ ὄνομα κυρίου Ἰησοῦ; 10, 48: ἐν τῷ ὀνόματι Ἰησοῦ Χριστοῦ; Gal. 3, 27: εἰς Χριστόν; Rom. 6, 3: εἰς τὸν Χριστόν).
The baptism "by authority of," or "into the name of," Christ, does not stand in opposition to the baptism into the name of the Triune God, since, on the one hand, Christ instituted the Sacrament, and, on the other, those who are baptized enter into communion with the Triune God only through faith in Christ. The two series of passages are therefore not exclusive, but inclusive; that is to say, he who is baptized is baptized by Christ's command into the Triune God through Christ Himself. In other words, we must never separate Baptism from Christ; it exists only because Christ commanded it, and it is efficacious only because it rests on His vicarious atonement, by which He secured all the spiritual blessings that are offered in Baptism.
This is the clear doctrine of St. Paul, who writes: "Christ also loved the Church and gave Himself for it that He might sanctify , and cleanse it with the washing of water by the word," Eph. 5, 25. 26. Baptism is therefore a sanctifying and cleansing water by virtue of the word (Gospel) connected with it, in which Christ freely offers to all men the merits which He secured when "He gave Himself" into death for the sins of the whole world. Every true baptism consequently is always in relation to Christ and because of this also in relation to the Holy Trinity.
Zoeckler, in his commentary on Acts 2, 38, rightly remarks that the apostles, when baptizing "in the name of Jesus," no doubt used the form prescribed in Matt. 28, 19, quoting in this connection the Διδαχή (7, 2. 3). This was in full accord with their constant insistence on the Triune God as the only true and living God and the Source and Author of all spiritual blessings, 2 Cor. 1, 13, 14, Eph. l, 2-14, 1 Pet. 1, 2-4.
It is immaterial whether the minister uses the formula "I baptize thee in the name of the Father, Son, and Holy Ghost" (Lutherans, Roman Catholics) or the one employed by the Greek Catholic Church: "This servant is baptized in the name of the Father, Son, and Holy Ghost." Even such a formula as "I baptize thee in the name of the Holy Trinity" is valid. But it must be borne in mind that the most fitting formula is that which comes closest to the words of institution. No minister should change the formula established in the Church, since deviations are bound to cause doubt and arouse disputation.
The question as to how we must regard baptismal acts performed by anti-Trinitarian heretics "in the name of the Father and of the Son and of the Holy Ghost" has been clearly and unanimously answered by all Christian teachers. Already St. Augustine reports that at his time heretics frequently baptized in the name of the Triune God, but that such a baptism was not recognized as valid by the Church.
Rejecting such a baptism is done on Scriptural grounds; for while it is true that in this case the name of the Holy Trinity is used, it is also true that such a use of God's name is only mockery and blasphemy, since these heretics do not believe in the God whose name they employ. Our dogmaticians therefore rightly contend that in all these cases God's Word is lacking, so that there is a "baptism" without the Word of God, and consequently no true baptism.
This case, of course, differs from one where an unbelieving minister (a hypocrite) serves a Christian congregation in that case his personal unbelief does not invalidate Baptism, since he, when administering Baptism, serves as the representative of the Christian Church.
It goes without saying that every baptism should be absolutely certain, so that the baptized may truly comfort himself with the covenant of grace established in Holy Baptism. In all cases of uncertainty the person in question must therefore be baptized. But this is not to be regarded as a second baptism or as a repetition of baptism, since an uncertain baptism is really no baptism. In conclusion we may say that we accept as valid all acts of baptism performed within and by professed Christian congregations.