John the Baptist prophesied in Matthew 3:11, "I indeed baptize you with water unto repentance: but he that cometh after me is mightier than I, whose shoes I am not worthy to bear: he shall baptize you with the Holy Ghost." This is consistent with the parallel passages in Mark, Luke, John, and Acts. Let's look at the Acts passage, for instance: "For John truly baptized with water; but ye shall be baptized with the Holy Ghost not many days hence" (Acts 1:5). Alright, so the baptism of the Spirit is being prophesied in the Gospels. To know what fulfillment we are to look for, we should consider those predictions. They provide the model for Spirit baptism. Who is the Administrator of this baptism? It is Jesus, the one whose shoes John was not worthy to bear. Jesus is the Administrator of Spirit Baptism. What is the element of the baptism? It is the Holy Spirit. The Holy Spirit is the Medium of Spirit Baptism. Who are the recipients of the baptism? They are already saved people. "You" is plural in Matthew 3, something you can't specifically see in the English. The plural "you" are people already saved and in certain cases, already baptized, saved people. So Spirit baptism according to the model is subsequent to, not simultaneous with salvation. That's what we should look for.
When we look at the fulfillment in Acts 2, that's what we see. Consider Acts 2:1-4a: "And when the day of Pentecost was fully come, they were all with one accord in one place. And suddenly there came a sound from heaven as of a rushing mighty wind, and it filled all the house where they were sitting. And there appeared unto them cloven tongues like as of fire, and it sat upon each of them. And they were all filled with the Holy Ghost." Who are these "they" mentioned? We must go back to the previous chapter, and we see that these were already saved people, already born again individuals, essentially the church at Jerusalem, even already baptized, who were then baptized with the Spirit on the Day of Pentecost. The element of the baptism was the Holy Spirit. We know that Jesus Christ sent the Holy Spirit, outpoured or sent Him on or to believers there in Jerusalem (John 15:26; 16:7). So, by looking at the prediction and the fulfillment, we get the model of Spirit baptism, and we are sure that Jesus is the Administrator, already saved people are the recipients, and the Holy Spirit is the Element or Medium.
Many, many professing believers and all "reformed" Christians believe that 1 Corinthians 12:13 teaches Spirit baptism. Let's find out if 1 Corinthians 12:13 fits the model predicted and fulfilled in the Gospels and Acts. This passage buttresses their belief in the universal, invisible church or the invisible body of Christ. Here's what it says: "For by one Spirit are we all baptized into one body, whether we be Jews or Gentiles, whether we be bond or free; and have been all made to drink into one Spirit." If this is Spirit baptism and not water baptism, it ought to fit the model. OK, first, Who is the Administrator of baptism here? The Holy Spirit. Well, zero for one, so far. Well, let's try a second, Who is the Medium of the baptism here? Hmmmmm, the body of Christ, so Jesus is the Medium or Element. Well, now we're zero for two. What about the recipients? We surely must get that right, especially with so much scholarship represented that takes this view. The reformed say that Spirit baptism is simultaneous with salvation, not subsequent, and the Spirit places us in the body of Christ. Hmmmm. So simultaneous with salvation, not already saved people, but people at the moment they are getting saved. Zero for three. Nothing in 1 Corinthians 12:13 says that this is Spirit baptism. What the passage does teach is that already saved people are water baptized into the body of Christ. Their baptism pictures their unity within the body. The body is a local church (see v. 27). Much more evidence exists contextually to say this is water baptism, immersion in deep, wet water.
Just a little theological snack to chomp on for now.