We should, first of all, establish that when we use the term 'Word of God', we are not referring to the Bible or even in that sense, the Scriptures themselves! The Pharisees made the fatal mistake of thinking that their Holy Writings constituted the Word of Life, but Jesus corrected them by saying, 'these are they which testify of Me' ( John 5:39 )! Earlier in his Gospel, John wrote concerning Jesus, 'In the beginning was the Word, and the Word was with God, and the Word was God' ( John 1:1 ) The English translations of Scripture that we call The Bible ( in its many forms ) does contain what we believe to be a more or less historical account of the Life of Jesus & maybe even more importantly, the History of Israel, but these words ( the Scriptures ) are simply they which tell of the Word of God, or the Word of Life!
We may trust the translations of man for the most part, although there are some very questionable translations & interpretations that have made their way down through the centuries & millenia since the original words were penned! The way it was explained by one theologian was, 'you can read the Gospel in most any version of the Bible'; in other words, the translators, most of them anyway, though they may use different terminology or omit & add certain words or accounts, have been more or less faithful to the Story as revealed in the Scriptures!
The Greek phrase that Timothy used to describe the Scriptures ( which, for his day, was what we call the Old Testament ) is transliterated 'theopneustos', a conglomerate, the middle of which has the same basic meaning as the Hebrew 'naphach', 'to breathe'. One might say therefore, that, just as the Creator breathed into the first Adam the Breathe of Life, so He breathed into certain men the Spirit of Inspiration in order that they might be able to pen, according to His Word!
The question was asked most recently, 'how do you decide which Scriptures pertain to us today, and which are merely historical reference?' Working from the belief that all of these Scriptures ( 'Old Testament', remember ) were fulfilled in the ministry of the Christ, while these Scriptures, as Jesus said, 'testify of Me', they still speak to us today for 'instruction in righteousness', for 'reproof' & for 'doctrine'. We have determined that the totality of what we read in the Hebrew Scriptures ( 'The Law & The Prophets' ) was brought to fulfillment in Jesus, while that pertaining to Israel under that first covenant simply passed away. The Greek Scriptures, in particular the Epistles of Paul, Peter, James & John, are instructive as well, though these too must be understood as having been fulfilled in & through the Body of Christ!
As these words were translated into our English Bibles, then, we can gain a greater understanding of the Nature of God. One might call this ( the Scriptures ) an Introduction of sorts! Just like a good book, though, we cannot get the whole Story by simply reading the Introduction; one must read the whole Story, from the first to the last chapter if one wishes to 'get' the whole Story!
Since our Creator has made His Home with us ( John 14:23 ), we now have the opportunity to nurture a more intimate Relationship with Him! The Bible, or Scripture, as it has been translated & handed down to us over many, many generations contains a more or less accurate representation of the Word of God, Jesus who was the Christ, but these Scriptures merely gave us a preview of our Heavenly Father & of His Only Begotten Son; they are not the Word Himself! As we read these words ( Scripture ), we may gain a deeper understanding of the nature & meaning of the History of Israel; through our study, we see how this history pointed to the Christ, was fulfilled in Him & is fulfilled in us today!
Charles Haddon Shank