ANSWER: It can only be “water baptism!” Obviously, the baptism in this passage is one of commandment. This means that everyone is commanded to be baptized. Holy Spirit baptism was never commanded, but, rather, it was a promise to be fulfilled (Acts 1:4-5). Since at the time of the writing of Ephesians 4:4 by the apostle Paul, there was clearly only “one baptism” and since the baptism of Matthew 28:18-20 was to be effective until the “end of the world,” it can only be concluded that the promise of Holy Spirit baptism was fulfilled prior to the writing of the book of Ephesians in 63/65AD. Also in 65AD, Peter wrote about water baptism being the baptism that “doth also now save us” (I Peter 3:20-21).

So then, Paul said in 63/65AD, there is only “one baptism!” Peter says at the same time that this one baptism is “water baptism.” We know further that the baptism of Matthew 28:18-20 is the only baptism that would continue until the “end of the world.” Therefore, the baptism spoken of in this passage can only be “water baptism.”