Thanks for the suggested wording. I will consider your wording, or whether I think I can improve on it. Perhaps it would be most accurate simply to say:It is dubious for one man to attempt to articulate the faith of another. But how about working with your first sentence:
"[T]he books [of the Old and New Testaments] have been given as a gift from God, who commissioned the prophets and apostles, and who revealed to them the things that they wrote."
The statement might need further work, on a few points:
(a) Do you hold that all books of the Old and New Testaments were written by prophets and apostles? Esther? Hebrews? Acts? I & II Kings?
(b) Are these books to be seen as direct gifts from G-d, or secondary effects of gifts from G-d? That is, does G-d purpose for books like these to be written, and arrange for such to occur? Or is it rather that G-d gave his world certain persons, who happened to write these books on their own initiative?
(c) Unless you wish to telegraph a plenary verbal revelation, the closing should be revised. Perhaps, "and who revealed to them the things that they wrote about."
"I believe the content of scripture was given by divine revelation to the Old Testament prophets and the apostles of Christ."
I am willing to accept the traditional authorship of the books of Kings, which is the Prophet Jeremiah. I don't know who wrote Esther. I assume that Mordecai was its principal source. My assumption is that Paul had in mind all the Old Testament books, including Esther and other books whose authorship is questionable (e.g., Chronicles, Ezra/Nehemiah) when he wrote that "all scripture" is "God breathed." If so, then he must have believed that all of those books were written under prophetic inspiration in some sense. If so, that would make their authors "prophets." (I would have to rework my assumptions if I were to become convinced that the better translation of 2 Timothy 3:16 would begin "All God-breathed scripture is profitable..."
I consider that book written by Luke, Mark and the writer of Hebrews were "apostolic, because of the close association these men had with the apostles Paul, Peter and Timothy, respectively. My assumption is that Luke could never have published his two books without Paul's approval—especially with the second book featuring Paul himself so prominently. The writer of Hebrews traveled with Timothy, which places him in Paul's circle. Mark, of course, had Peter's authority behind his book.