Does the Christian need additional revelations, visions, words of prophecy, or insights from modern psychology? Some people think so. No, says @Aspree of Berean Research. Scripture is sufficient. She explains why:
Did you know that the Bible is all we need to equip us for a life of faith and service? It’s true! And in fact the doctrine of the sufficiency of Scripture is a fundamental tenet of the Christian faith. Sadly, it’s a tenet that has long been under viscous attack from within our own visible, modern churches.
But be assured that no other writings are needed for the Gospel to be understood, nor are any other writings required to equip us for a life of faith. Everything else – entertainment, extra-biblical revelations, mysticism, spiritual deliverance ministries and some forms of psychological counseling all declare that the Bible and its precepts are not enough. But Jesus said, “My sheep hear my voice and I know them and they follow me” (John 10:27). His voice is found in every word of the Word; the Scriptures are His voice, completely and utterly sufficient.
Consider 2 Timothy 3:15–17: