The author of Hebrews describes the word of God as something so sensitive that it can "read" our thoughts and motivations, and something so precise that it can divide the physical and spiritual. In a way, the word of God serves as both a sensor and a scalpel.
Similar to any medical instrument that monitors the well-being of a patient, God’s word monitors our spiritual well-being. It "discerns our thoughts and intents," alerting us when our motivations or actions are becoming unhealthy. For this sensor to be effective, we have to keep ourselves "hooked up" to it by constantly reading and meditating on God’s word. If we fail to do this, God’s word cannot do its job and detect the sin that has begun to creep into our lives.
Oftentimes, this sensor will pick up maladies like resentment, lust, envy, or pride. Or it may detect something (or someone) that has begun to supersede God’s place in our lives, somewhat like spiritual cancer. This is when God’s word must become a scalpel. We must allow it to perform surgery in our lives, cutting out the sin or the wrong intentions that have begun to grow, or ultimately the sin will kill us.
Performing surgery may mean removing the things from our lives that have caused us to sin. Jesus says in Matthew 5:29 that "if your right eye causes you to sin, pluck it out and cast it from you; for it is more profitable for you that one of your members perish, then for your whole body to be cast into hell." If even our eye is not worth keeping, how much more should we get rid of the cable service, alcohol, magazines, or anything else that might cause us to sin!
Surgery may also entail rearranging our priorities and giving God first place in our hearts. Perhaps a favorite pastime has overshadowed our time and devotion for God. Or perhaps someone has begun to take God’s rightful place in our lives. In this case, we need to supplant these worldly desires with the desire for God.
It takes courage to allow God’s sensor and scalpel to do its job in our lives. Sometimes it will hurt, and sometimes it will bleed. But if we are willing to cut out sin and pursue God wholeheartedly, we will ultimately receive "the crown of life which the Lord has promised to those who love him" (Jas 1:12).