Once upon a time I went through and underlined every time “word of God” was used in the book of Acts. The phrase occurred quite often in passages about evangelism, which of course is a theme of Acts. At the time I was accumulating evidence that if we wanted to be effective at converting the lost, we needed to use actual Scripture instead of our emotional phrases and cute metaphors. A passage in 2 Timothy inspired me: “And that from Childhood you have known the Holy Scriptures of God, which are able to make you wise for salvation…”
Having been raised in the evangelical church, I didn’t at that time ask an obvious question. When the apostles, Paul, the deacons, and all those famous evangelists spoke “the word of God,” to what did that refer? Did they stand up in front of masses of Greeks and compile quotations from Exodus, Psalms, and Habakkuk to call men to faith in Jesus? Obviously they did not yet have the New Testament written. We do have some examples of the apostles quoting the Old Testament to people while preaching. And there’s the story of Philip, who found the Ethiopian Eunuch reading Isaiah, so he explained how what we know as chapter 53 was a prophecy fulfilled by Jesus, and led him to salvation from there.
I’m skeptical that “the word of God” could have been referring to the Old Testament. There are words to refer to those writings: Scripture, Prophets, Law, Moses, Isaiah, “as it is written.” But Acts didn’t use those to describe the apostles’ preaching.
Ok, Jesus when He was being tempted quoted to the Devil that man lives by “every word that proceeds from the mouth of God.” Jesus Himself was using Scripture, so we usually interpret this as an exemplary double-punch. I don’t need bread; I need exactly what I’m using now: Scripture. Except, well, what did the original author mean, the one whom Jesus was quoting?
If you go to the Psalms, all over the place you find references to the “word of the LORD.” David says he delights in “Your word.” Does he mean only that he delights in the Law of Moses? Why do we think of something different when we read, “The word of the LORD came to…” the prophets?
When Jesus reaffirmed that man lives by “every word that proceeds from the mouth of God,” was He including the words God would speak during His earthly ministry? Did He mean also those words that He heard from the Father and spoke obediently? What about the New Testament, which we are today taught is God-breathed just like the Old Testament? Are we to live by any other “words from God?” I mean, if the apostles were preaching the “word of God” in Acts, and that didn’t just refer to what had been previously expressed in the Scripture or by Jesus, why don’t we have those preached words recorded? Do we need them? John supposes that if everything Jesus said and did were recorded there wouldn’t be books enough to contain them; why don’t we need all the words that Jesus spoke?
To God be all glory.