How do we know that believer's baptism is biblical?

In Ephesians 4:5, scripture underscores that there is 'one Lord, one faith, and one baptism.' This unifies the baptism that John performed and the baptism practiced by believers today. In Acts 19, when Paul encounters those baptized under John's ministry, he clarifies that they were to believe on Christ. This showcases that John's baptism was not just a ritual but a significant confession of faith in the impending sacrifice of Christ, which correlates with the believer's baptism practiced in the early church, confirming its biblical basis.