What is the word of God?

Answer: The holy scriptures of the Old and New Testaments are the word of God,[1] the only rule of faith and obedience.[2]

1. II Tim. 3:16:

   All Scripture is breathed out by God and profitable for teaching, for reproof, for correction, and for training in righteousness...

   II Peter 1:19-21:

   And we have something more sure, the prophetic word, to which you will do well to pay attention as to a lamp shining in a dark place, until the day dawns and the morning star rises in your hearts, knowing this first of all, that no prophecy of Scripture comes from someone's own interpretation. For no prophecy was ever produced by the will of man, but men spoke from God as they were carried along by the Holy Spirit.

2. Eph. 2:20

   built on the foundation of the apostles and prophets, Christ Jesus himself being the cornerstone

   Rev. 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.

   Isa. 8:20

   To the teaching and to the testimony! If they will not speak according to this word, it is because they have no dawn.

   Luke 16:29, 31

   But Abraham said, ‘They have Moses and the Prophets; let them hear them.’ ...He said to him, ‘If they do not hear Moses and the Prophets, neither will they be convinced if someone should rise from the dead.’”Answer: The holy scriptures of the Old and New Testaments are the word of God, [1] the only rule of faith and obedience.

   Gal. 1:8,9

   But even if we or an angel from heaven should preach to you a gospel contrary to the one we preached to you, let him be accursed.
   
   As we have said before, so now I say again: If anyone is preaching to you a gospel contrary to the one you received, let him be accursed.

   II Tim. 3:15-16

   ...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...

From the Westminster Larger Catechism.