What does the Scripture mean in Hebrews 4:12 relating to a two-edged sword?
"For the word of God is living and powerful, and sharper than any two-edged sword, piercing even to the division of soul and spirit, and of joints and marrow, and is a discerner of the thoughts and intents of the heart" (Hebrews 4:12).
The emphasis in this passage is on the fact that a two-edged sword is sharp. In comparison, God's word is even sharper because it can divide or make a distinction between things we generally think of as being closely related or indistinguishable. For example, what is the difference between a soul and a spirit? What is the difference between a person's thoughts and intentions?
God's word is able to penetrate to the heart of a person and cause a change, and unlike a physical sword, it leaves no external scar. That is why you find those hearing Peter's message responding, "Now when they heard this, they were cut to the heart" (Acts 2:37).
Another thing to remember is a two-edged sword is considered to be a dangerous weapon because of the two edges. Handled improperly it can cut the wielder just as easily as it can cut someone else. When the Bible is used as a weapon to point out the flaws in another person, the person using it often finds himself convicted by the same word. "You, therefore, who teach another, do you not teach yourself? You who preach that a man should not steal, do you steal? You who say, "Do not commit adultery," do you commit adultery? You who abhor idols, do you rob temples?" (Romans 2:21-22).