I've dropped the ball on my investigation of the authority of God in the Bible, and I may just give it up as I don't think I'm going to have time to do it right any time soon, but I did have occasion to investigate the use of the idea of "word of God" in the Bible.
In the NRSV, the phrase "word of God" appears only three times in the Old Testament, but the phrase "word of the Lord" appears 238 times. Because of the volume, I won't treat each passage individually.
What I will say is that in the overwhelming majority of cases (and arguably all) where these two phrases are used in the Old Testament they are being used to reference something other than Scripture. Specifically, in most cases these phrases refer to a sort of power by which God influences the world. Most specifically, more than half of the instances refer to the power of God coming to or speaking through prophets.
In 109 instance, the use is of the form "the word of the Lord came to X." An additional 34 times someone speaking says something of the form "hear...the word of the Lord." Another 27 times, something happens "according to the word of the Lord" often in fulfillment of a prophetic announcement. And 10 times, something is said to be done "by the word of the Lord." That's 180 of the 241 uses just with those specific formulas. The other uses are generally also of this sort, including people keeping the word of the Lord and other people rebelling against the word of the Lord.
In the New Testament, the phrase "word of God" is much more common, but once again it rarely refers to Scripture. The phrase "word of the Lord" occurs 15 times in the NRSV New Testament, the phrase "word of God" occurs 37 times and the phrase "word of Christ" occurs twice.
I have gone through these occurences and classified them according to what they refer to.
I find only one verse which I think can be argued to directly refer to Scripture using the phrase "word of God", Mark 7:13, "thus making void the word of God through your tradition that you have handed on. And you do many things like this." This verse is clearly referring to what God has commanded. That could, quite reasonably, be understood as meaning scripture.
In two more cases (Lk 8:21 and Lk 11:28) the phrase "word of God" refers to the will of God that is heard. Again, this could arguably be understood as Scripture, but only in a limited sense. When Jesus speaks of "those who hear the word of God and do it" this cannot be a general reference to Scripture, for not everything in the Bible can be done as such.
In one case (Rev. 19:13) the term "Word of God" refers to Jesus Christ himself. In one more (Lk 5:1) "word of God" refers to what Jesus is saying. In two cases (Lk 22:61 and Acts 11:16) the phrase "word of the Lord" refers to something specific Jesus had said.
In five instances (Lk 3:2, 1Co 14:36, Col 1:25, 1Th 4:15, Rev 1:2) "word of God" seems to refer to the prophetic concept, as in "the word of God came unto John". In two cases (Heb 11:3, 2Pe 3:5) "word of God" refers to the creative word of God, as in God spoke and it was so.
In three significant cases (Ac 6:7, Ac 12:24 and Ac 19:20) "the word of God" or "word of the Lord" is described as something apparently insubstantial that spreads, advances and even grows as the Gospel is spread.
The overwhelming majority of the cases in the New Testament (31 occurences) are those in which "word of God" or "word of the Lord" refers to preaching or otherwise bearing witness to Christ. These include cases where people "praised" the word of the Lord (Acts 13:48) that they have heard, cases where the word of God is "received", a case (1Pe 1:23) which speaks of "the living and enduring word of God" by which people are born anew and another (1Pe 1:25) in the same context which says that "the word of the Lord endures for ever" and, lest we be confused, says "That word is the good news that was announced to you."
The full list which I have classified as cases of preaching or witness is:
Ac 4:31, Ac 6:2, Ac 8:14, Ac 8:25, Ac 11:1, Ac 13:5, Ac 13:7, Ac 13:44, Ac 13:46, Ac 13:48, Ac 13:49, Ac 15:35, Ac 15:36, Ac 16:32, Ac 17:13, Ac 18:11, Ac 19:10, Ro 9:6, Ro 10:17, 1Th 1:8, 1Th 2:13, 2Th 3:1, 2Ti 2:9, Tit 2:5, Heb 6:5, Heb 13:7, 1Pe 1:23, 1Pe 1:25, Re 1:9, Re 6:9, Re 20:4
That leaves the following six verses, which I have classified as debatable. It could be argued that these are references to Scripture, but I think, in light of the above analysis and the principle that Scripture interprets Scripture, that it makes far more sense to understand these all as the powerful presence by and through which God achieves his will in the world.
Now the parable is this: The seed is the word of God.
If those to whom the word of God came were called 'gods'—and the scripture cannot be annulled—
Take the helmet of salvation, and the sword of the Spirit, which is the word of God.
Let the word of Christ dwell in you richly; teach and admonish one another in all wisdom; and with gratitude in your hearts sing psalms, hymns, and spiritual songs to God.
Indeed, the word of God is living and active, sharper than any two-edged sword, piercing until it divides soul from spirit, joints from marrow; it is able to judge the thoughts and intentions of the heart.
I write to you, children, because you know the Father. I write to you, fathers, because you know him who is from the beginning. I write to you, young people, because you are strong and the word of God abides in you, and you have overcome the evil one.