Q. Is it correct to say that whenever God speaks in the Old Testament, such as “Thus says the LORD,” it is usually the Father speaking, but on some occasions it may be the Son or the Holy Spirit? Or is it more correct to say it is always the Father speaking? Or is there a better way to view this?
I think the general theological principle involved here is that the members of the Trinity, even though they are distinct persons, do things together. We see this, for example, in the creation account at the beginning of the Bible. It says, “In the beginning, God created the heavens and the earth” (likely referring to God the Father). But this account then relates how the Father created by speaking, which would be the cooperative activity of Jesus, the Word. As the gospel of John says, “In the beginning was the Word … all things were created by him.” And in that account we also see the activity of the Holy Spirit: “the Spirit of God was hovering over the waters,” surveying the dark, formless world and no doubt planning how to bring order and light to it. So all three persons of the Trinity were involved together in the first divine action that the Bible relates, and I think that continues to be the case as the Bible progresses.
Even when the second person of the Trinity comes to earth and takes on human form, we continue to see this type of co-operation. Jesus said after one of his great healing miracles, “The Son can do nothing by himself; he can do only what he sees his Father doing, because whatever the Father does, the Son also does.”
I would apply this same principle to the instances of divine speech in the Old Testament. I think they are further examples of co-operation on the part of the Trinity. Interestingly, the book of Hebrews attributes to the Holy Spirit an oracle in Jeremiah that is originally spoken by “the Lord Almighty, the God of Israel,” who says of himself in that same oracle, “I am Israel’s father.” Hebrews says:
The Holy Spirit also testifies to us about this. First he says:
“This is the covenant I will make with them
after that time, says the Lord.
I will put my laws in their hearts,
and I will write them on their minds.”
Then he adds:
“Their sins and lawless acts
I will remember no more.”
But, as I noted, when God speaks these words in Jeremiah, the identification we have of him seems to be that of the Father. But this is not inconsistent with the principle of co-operation among the persons of the Trinity.
Hope this is helpful!
Good Question 