Certain genres of Scripture seem to relate more directly to different "power words" we use about Scripture more than others.
1. Infallible seems to be an umbrella term in the sense that no part of Scripture fails to do what God wants it to do. But what does God want each part of Scripture to do?
2. The commands of Scripture are authoritative, but their purpose is not to make us do them, because God has given the freedom to disobey for now. So the purpose of the commands of Scripture was to give God's will at specific times and places, as well as for all time. There are time-specific commands in Scripture too, however, such as the command to Israel not to eat pork. God did not intend it to apply to today. So God did not intend all the commands of Scripture to be "all time." Some were "that time."
3. God's promises do not fail either. But not all of God's promises were unconditional. God tells the Ninevites he will destroy them. But it was a conditional prediction. After they repent, he does not destroy them.
4. God's purposes in the stories of Scripture were often to reinforce the identity of his people. In keeping with the original contexts of Scripture, their purpose was not primarily to tell history according to our modern sensibilities. That is more of a modern concern. Biblical stories often involved moral lessons for Israel or identity-confirming elements. In the New Testament, the stories help establish the Christian metanarrative.
5. God's purposes in many psalms seem to be to provide an expression for God's people of thanksgiving, lament, and anger, as well as to facilitate the worship of Israel. Their purpose is not primarily to teach or to identify but to express. They also give hope. They help God's people vent and express strong feelings.
6. In some cases, God's purposes are to inform. In such cases, the Bible is inerrant. This is the minority function of Scripture, although modern Western culture, unaware of itself, has sometimes assumed this is the major, perhaps even the only function of Scripture. But the main purpose of Scripture is not to give the answers to a test. Even in those cases where the Bible gives information, God gave that information within the categories of its original audiences, within their ancient worldviews. The Bible thus does not give specific answers to the make-up of human psychology or cosmology. It presents other truths or does other functions within the cosmological and psychological paradigms of its own ancient audiences.
7. To speak of the Bible's inspiration is to say that it unfallingly accomplishes what God intended and intends it to do. Sometimes people imagine inspiration in a premodern caricature, where an individual sits down and the Spirit takes over the stylus to write words. The inspired meaning thus pictured is then often not the original meaning, but a meaning seen in the text by the later reader. Inspiration in history was far more three-dimensional than this two-dimensional caricature.
Even in the NT, when 2 Timothy 3:16 speaks of the God-breathed nature of the OT, it does not refer necessarily to the contextual meaning of Scripture but includes the meanings that the Spirit breathes through Scripture above the contextual one. When Paul hears a word about the material support of ministers in Deuteronomy 25:4, he is hearing an inspired metaphorical meaning that goes beyond the original sense of oxen treading grain.
2 Timothy 3:16 thus cannot be used to argue for a fundamentalist agenda, which tries to constrict the sense of inspiration to a quasi-literal straight jacket. Rather, God inspired the words of Scripture originally, working with the authors' minds, to do what he wanted it to do, and the Holy Spirit continues to inspire readers' minds today for Scripture to do what he wants it to do.
8. Ultimately, God can do in us whatever he wants to do in us. As Wesley suggested, God uses Scripture as a means of grace. It is a sacrament of transformation, by which God changes and transforms us. Ultimately, God can do whatever he wants in us with any Scripture, regardless of genre, regardless of what it originally meant.