'Old Testament' in the Bible

God had promised this good news a long time ago through His prophets [and had it written] in the holy Scriptures [i.e., the Old Testament].

Now we [all] know that everything the law says applies to those who are under [obligation to obey] that law, [Note: Here "the law" appears to refer to the Old Testament Scriptures generally, since Psalms and Isaiah are quoted. See verses 10-18]. This is so that the mouth of every objector may be stopped [i.e., from making excuses for his sin], and thereby bring the entire world under God's judgment [i.e., both Jews and Gentiles].

[Note: The following are rhetorical questions raised from their reading of the Old Testament]. For who has known [what goes on in] the Lord's mind? Or, who has been His advisor?

For whatever things were written previously [i.e., in the Old Testament], were intended for us to learn from, so that we could have hope [i.e., in the face of difficult times] through remaining steadfast, and through the encouragement [received] from reading the Scriptures.