Contradiction with Matthew 28:19
While John 3:26 mentions John the Baptist baptizing, Matthew 28:19 contains the Great Commission, directing the disciples, not John, to baptize all nations in the name of the Father, Son, and Holy Ghost.
Matthew 28:19: Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost: [teach...: or, make disciples, or, Christians of all nations]
Contradiction with Acts 19:2-4
In these verses, Paul encounters believers who have only been baptized into John's baptism, which lacks the Holy Spirit, contradicting the implication in John 3:26 that John's baptism was sufficient or complete.
Acts 19:2-4: He said unto them, Have ye received the Holy Ghost since ye believed? And they said unto him, We have not so much as heard whether there be any Holy Ghost.
Contradiction with John 4:2
This verse states that Jesus Himself did not baptize, but His disciples did, contrasting with the emphasis on John's disciples baptizing in John 3:26, highlighting a shift from John's to Jesus' baptism.
John 4:2: (Though Jesus himself baptized not, but his disciples,)
Contradiction with 1 Corinthians 1:14-17
Paul declares gratitude for baptizing few people and emphasizes preaching the gospel over baptism, contradicting the implication in John 3:26 of the centrality of baptism conducted by John's disciples.
1 Corinthians 1:14-17: I thank God that I baptized none of you, but Crispus and Gaius;