Indeed, the word of God is living and active, sharper than any two-edged sword, piercing until it divides soul from spirit, joints from marrow; it is able to judge the thoughts and intentions of the heart. (Hebrews 4:12)
This is one of the Bible verses I learned as a new Christian; we memorized it as a verse that describes the importance of the Bible (“the word of God”). But in context, this verse is giving a reason why we should not “harden our hearts” and fall short of the Sabbath rest God has promised for us. God can precisely discern what is in our hearts and souls, and God will decide and then declare whether we are to enter into God’s rest. The image changes from “word” to “sight” in verse 14: “And no creature is hidden from his sight, but all are naked and exposed to the eyes of him to whom we must give account.” Thus, “the word of God” must be more than just Scripture itself, but all of God’s judgments and wisdom.
Very fortunately, by the way, lest we despair at our inability to pass God’s judgment, the very next verse reminds us that we have “a great High Priest,” Jesus, the Son of God, from whom we can thus “receive mercy and find grace to help in time of need.”