How is the Bible true?
"Since many have undertaken," St. Luke begins his gospel, "to set down an orderly account of the events that have been fulfilled among us, I, too, decided... to write an orderly account for you, most excellent Theophilus, so that you may know the truth concerning the things about which you have been instructed: (1:1, 3-4).
In a sense we are all "Theophiluses": lovers of God who seek the true God and want to know what kind of relationship God draws us into. So if scripture is one of the ways that communicates these truths, then it must also in some way be true. But how?
One reason Catholics and other Christians say the Bible is true is because it is revelation. Believing scripture to be revelation means that, if you wisely interpret it, you can trust it to tell you who God is and to what God calls humanity. In this regard, the Second Vatican Council's Dogmatic Constitution on Divine Revelation (Dei Verbum) declares, "The books of scripture must be acknowledged as teaching solidly, faithfully, and without error the truth that God wanted put into the sacred writings for the sake of our salvation."
Another way the church considers the Bible to be true is because it is inspired. God did not so much guide the hands of the biblical authors as act on their minds and hearts to make known a message about God's activity in the world.
The process that produced the Bible was a dynamic one that occurred over time. The truth of scripture is also a process something we have to discover. Though scripture may be divinely inspired and guided, it is also humanly written, so readers of scripture need to take advantage of the best scholarly knowledge to understand the intentions of the original authors and translate the original message to their own situation.
Scripture is not handed to us on a plate in the form of a statement of truths or a collection of moral principles. "The Bible," as the Pontifical Biblical Commission wrote in The Interpretation of the Bible in the Church, "in effect, does not present itself as a direct revelation of timeless truths but as the written testimony to a series of interventions in which God reveals himself in human history."
Scripture helps us to "know the truth," in Luke's words, because it offers, through inspired experiences and authors, a trustworthy story of what we need to know about God and how God has entered human life. It's a story we, like Theophilus, can understand and believe.