Reformed Baptists unequivocally deny any new revelation beyond Scripture or any binding extra-biblical source of doctrine. The principle of sola scriptura — Scripture alone — is foundational to Reformed Baptist theology. Scripture is self-attesting, self-interpreting, and wholly sufficient for faith and practice. The 1689 London Baptist Confession declares that Scripture contains all things necessary for salvation and that nothing is to be added to or taken from it.

Reformed Baptists affirm cessationism: the miraculous sign gifts (prophecy in the authoritative apostolic sense, speaking in unknown tongues, divine healing as a sign gift) ceased with the completion of the canon and the apostolic era. These gifts authenticated the apostolic office and message in the early church. Once the New Testament was completed and widely distributed, the sign gifts were no longer needed and disappeared from the church.

This does not mean the Holy Spirit is inactive or that God does not speak in the present. He speaks through his written Word, illuminating believers' minds to understand Scripture and apply it to their lives. The Spirit guides the church through the preaching of the Word, prayer, and the counsel of godly leaders. However, no contemporary prophecy, dream, or vision may contradict or add to Scripture. The test of any claimed revelation is whether it aligns with Scripture; if it does not, it is false.