We pledge ourselves to the prophetic and apostolic writings of the Old and New Testaments as the pure and clear fountain of Israel, which is the only true norm according to which all teachers and teachings are to be judged and evaluated. - Christian Cyclopedia
The Protestant doctrine of sola scriptura (Scripture alone) teaches that every doctrine in Christian theology must be derived from Scripture alone. This teaching is not based on only a few Bible passages or "proof texts", but rests on a great number of Bible sections and verses that touch on the subject. When everything that the Bible says about the source of religious truth and the authority to establish teachings among God's people is taken into account, we hold that it becomes clear that we are to base our doctrine and practice on Scripture alone. - WELS
II Tim. 3:14-17 But as for you, continue in what you have learned and have firmly believed, knowing from whom you learned it and how from childhood you have been acquainted with the sacred writings, which are able to make you wise for salvation through faith in Christ Jesus. All Scripture is breathed out by God and profitable for teaching, for reproof, for correction, and for training in righteousness, that the man of God may be competent, equipped for every good work.
Revelation 22:18-19 I warn everyone who hears the words of the prophecy of this book: if anyone adds to them, God will add to him the plagues described in this book, and if anyone takes away from the words of the book of this prophecy, God will take away his share in the tree of life and in the holy city, which are described in this book.