Before His ascension into heaven, the risen Lord Jesus Christ gave orders to His own as follows: “All power is given unto me in heaven and in earth. Go ye therefore and teach all nations, baptizing them in the name of the Father, and of the son, and of the Holy Ghost; teaching them to observe all things whatsoever I have commanded you, and lo, I am with you alway, even unto the end of the world. Amen” (Matthew 28:18-20).
We assume that the baptism mentioned here is the distinctively Christian ordinance, separate and different from John's baptism that went before, or any other baptism.
We also assume its abiding force until the Consummation.
We also assume that it is water baptism.
We do so with good reason; only, how can we prove these assumptions true?
Actually, in Matthew 28:19, the baptism is in the Name of the Father and of the Son and of the Holy Spirit. Those who become disciples are to be baptized in (lit. into) the triune name. They are baptized in the name of the triune God because they belong to God, having been brought into the new covenant that expresses the will of the triune God.
Now a sacrament is a means of grace, for God uses it to strengthen faith's confidence in His promises and to call forth acts of faith for receiving the good gifts signified.
Not as if the rite of baptism as such brings a person into vital union with the Father, Son and Holy Spirit. But, according to Scripture the following are true:
1. Circumcision was a sign and a seal of the righteousness of Christ accepted by faith (see Rom.4:11 in its context);
2. Baptism is parallel to circumcision (Col.2:11,12);
3. Therefore baptism, too, must be regarded as a sign and a seal of the righteousness of Christ received by faith.
4. Furthermore, circumcision was performed by men upn men, but it signified a spiritual operation that only God could perform upon man's soul. By the same token, water baptism is performed by men upon believers, signifying a spiritual baptism (1 Cor.12:13) that only God could perform.
Though we cannot prove from the text itself that it is water baptism we readily notice that the apostles so understood the Great Commission, for everywhere they went, and everyone who received the message was baptised in water, as a sign of of the thing signified, that is, of being introduced in the body of Christ and having the forgiveness of sins, of dying with Christ and being raised with Him also, to walk in newness of life. The Acts contain many instances where the apostles baptised believers with water (for instance, 2:41; 8:36-40; 9:18; 10:44-48; 16:15,33). And even before the Resurrection, the disciples baptised with water, and in no other element, John 4:1,2).
Baptism is very important. The one who submits to it, if sincere, is proclaiming that he has broken with the world and has been brought into union with the Triune God, to whom he intends to devote his life.
Now my argument is this: if this sublime work is entrusted in the hands of men (by baptism), then for all practical purposes the apostles saved men, something that is reserved for the Holy Spirit to do. It's God's prerogative to bring men in union with Himself, just as it is His prerogative to forgive sins. So Baptism in Matthew 28 cannot mean Spirit-baptism, since it is entrusted into man's hands. We are entrusted with the preaching of salvation, not with the dispensing of it (as Roman Catholics blasphemously claim).
So since we are bound to employ the analogy of faith (comparing Scripture with Scripture) the natural, logical and inescapable conclusion must be that Christ was referring to water baptism in His Great Commission.
One last point: How may a nation be baptized in water? We observe that the same Greek word "ethnos" is often translated "Gentiles." Christ is not here alluding to mass conversions of whole nations as Roman Catholics are notoriously known to have imposed upon the nations, as in South America and in Europe during the Dark Ages. No, faith must always be individual and personal. So Christ is here referring to the discipling of not only Jews, but people from all over the world. The promise that in Abraham all the nations would be blessed (Gen.12:3) is ready to be fulfilled.