“For the word of God is alive and exerts power and is sharper than any two-edged sword and pierces even to the dividing of soul and spirit, and of joints from the marrow, and is able to discern thoughts and intentions of the heart.”—Hebrews 4:12, New World Translation.

 “For the word of God is living and active, sharper than any two-edged sword, piercing to the division of soul and of spirit, of joints and of marrow, and discerning the thoughts and intentions of the heart.”—Hebrews 4:12, English Standard Version.

 God’s message to humankind, as recorded in the Bible, has the power to reveal our true thoughts and motives. That message can also change people for the better.

 “The word of God is alive.” The expression “the word of God” refers to God’s word of promise, or his stated purpose, as recorded in the Bible. a An important aspect of that purpose is for obedient humans to live forever on earth in true peace and unity.—Genesis 1:28; Psalm 37:29; Revelation 21:3, 4.

 How is God’s word, or his expressed purpose, “alive”? For one thing, it has a powerful effect on the hearts of those who accept it, giving them hope and a purpose in life. (Deuteronomy 30:14; 32:47) God’s word of promise is also “alive” in that the living God is working toward the complete fulfillment of his promises. (John 5:17) Unlike humans, God does not make a promise and then forget about it or discover that he is unable to fulfill it. (Numbers 23:19) His word “will not return to [him] without results.”—Isaiah 55:10, 11.

 “The word of God . . . exerts power.” The expression “exerts power” can also be rendered “is powerful,” “is active,” or “accomplishes whatever [that word] is intended to accomplish.” Therefore, anything Jehovah b God says or promises is sure to be fulfilled. (Psalm 135:6; Isaiah 46:10) In fact, God can fulfill his promises in ways that far exceed our expectations.—Ephesians 3:20. c

 God’s word also “exerts power” by helping those who appreciate its value to make positive changes in their life and personality. God’s teachings become part of them, influencing their thinking, lifestyle, and goals. (Romans 12:2; Ephesians 4:24) In that sense, “the word of God . . . is also at work in” those who accept it as such.—1 Thessalonians 2:13.

 “The word of God . . . is sharper than any two-edged sword.” Figuratively speaking, God’s word is sharper than any man-made sword because of its penetrating power. God’s message can reach the heart—the inner person—in ways that no human teaching can. This is revealed in what Hebrews 4:12 goes on to say.

 “The word of God . . . pierces even to the dividing of soul and spirit, and of joints from the marrow.” In the Bible, “soul” can refer to who the person appears to be, whereas “spirit” can refer to who he really is inside. (Galatians 6:18) Figuratively speaking, “the word of God” penetrates right to “the marrow,” our very deepest feelings and thoughts. By revealing who we truly are on the inside, where no human can see, Jehovah’s teachings can move us to make positive changes. This brings joy both to our Creator and to us.

 “The word of God . . . is able to discern thoughts and intentions of the heart.” The way a person responds to God’s word can reveal his true thoughts, even his very intentions or motives, which influence his behavior or conduct. For example, if a person responds positively to God’s word by making needed changes in his life, he shows that he is humble and sincere. He wants to please his Creator. On the other hand, if he tries to find fault with God’s word, he may be revealing negative traits, such as undue pride or selfishness. Perhaps he is trying to justify conduct that God disapproves.—Jeremiah 17:9; Romans 1:24-27.

 As one reference work says, the word of God “can reach to the innermost recesses of our being.” There is no aspect of the inner person that God cannot see and that his word cannot bring to light. “All things are naked and openly exposed to the eyes of the one to whom we must give an account,” says Hebrews 4:13.

 Written by the apostle Paul in about 61 C.E., the Bible book of Hebrews is a divinely inspired letter to Jewish Christians in Jerusalem and Judea.

 In chapters 3 and 4, Paul highlights how the example of the ancient Israelites serves as a warning for Christians. (Hebrews 3:8-12; 4:11) Jehovah promised to rescue the Israelites from slavery and to settle them in a land where they could “dwell in security.” (Deuteronomy 12:9, 10) However, the generation of Israelites that left Egypt repeatedly showed a lack of faith in God’s promises and routinely disobeyed his commandments. As a result, they did not “enter into [God’s] rest” and enjoy a peaceful relationship with God. Instead, they died in the wilderness. Although their descendants inherited the Promised Land, they too fell into a pattern of disobedience. In time, this cost the nation dearly.—Nehemiah 9:29, 30; Psalm 95:9-11; Luke 13:34, 35.

 Paul explains that Christians should learn from the bad example of the unfaithful Israelites. Unlike them, we can enter into God’s rest by obeying his word and by having complete faith in his promises.—Hebrews 4:1-3, 11.

 Watch this short video to see an overview of the book of Hebrews.