Only unitarians and apostates practised ‘rebaptism’ in the apostolic age. Mark 7:3-8; Acts 19:1-3; First Corinthians 11:18f & 15:29. To the True Visible Church of the Triune God, there was only one baptism — trinitarian, life-long, and unrepeatable. Matthew 28:19f; Mark 16:15f; Romans 6:3-23; Ephesians 4:4-6; Colossians 2:6-16.
Hebrews 6:1-6 implies that those who get themselves rebaptized, recrucify Christ. For it commands: “Do not again lay down…the doctrine of baptisms…. They crucify to themselves the Son of God afresh!” See Francis Nigel Lee: Rebaptism Impossible.
The Westminster Confession of Faith 28:7 declares that “the sacrament of baptism is but once to be administered to any person. Titus 3:5.”
