***Ephesians 4:4 says that there is "one baptism"***
But John said there are two...
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, and with fire:
***since the Holy Spirit baptism is only administered by Jesus***
To all believers, right?
The baptism of fire that John is referring to is a fulfillment of a prophecy from Joel. It was fulfilled at Pentecost (Acts 2) and later with Cornelius and his family (Acts 10).
Paul's mention of "one baptism" in Ephesians 4 is clearly the baptism that puts us into the "one body", which is the baptism administered to the people in Acts 2:38-41.
When a person believes, has repented of their sins, confessed that Christ is the Son of God, and been baptized for the remission of sins, they receive the Holy Spirit(Acts 2:38).