Is the baptism in 1 Corinthians 12:13 a water baptism?
No. First Corinthians 12:13 describes Spirit baptism, not water baptism. The one Spirit, the Holy Spirit, baptizes every believer into the body of Christ, inundating them in Christ the moment they believe the Gospel. Water is not the element; the invisible Holy Spirit is.
Les teaches that 1 Corinthians 12:13 is not a water baptism. He pauses to define "baptized" as being inundated or completely inundated. He illustrates this with a Greek classical writer who spoke of a ship being baptized at sea: the ocean water filled every crook and cranny as it sank. But here the element is not water; it is the invisible person of the Godhead, the Holy Spirit, who has inundated believers in Christ. This happens the moment a person believes the Gospel, and you don't feel a thing.
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.