What does Luke 6:45 mean?
Just as only a good tree can bear good fruit and a grapevine produce grapes, so only a good heart can produce good. We can tell if someone has a bad heart by listening to their words. Like the bramble that produces nothing but thorns (Luke 6:44), they will revile believers and praise others who join them (Luke 6:22, 26). They will curse their enemies and demand their rights (Luke 6:28–30). They will be quick to judge and condemn others, but their false words will lead their followers into a pit (Luke 6:37, 39). This is the overall point of Jesus' recent metaphor.James is even more graphic. He says, "So also the tongue is a small member, yet it boasts of great things. How great a forest is set ablaze by such a small fire! And the tongue is a fire, a world of unrighteousness. The tongue is set among our members, staining the whole body, setting on fire the entire course of life, and set on fire by hell" (James 3:5–6).
For this reason, teachers should be cautious; they will be judged more harshly than others because their words can do more damage (James 3:1; Luke 6:39–42).
Christ-followers with good hearts will speak words as sweet as a fig from a fig tree or a grape from a vine (Luke 6:44). They will bless and pray for their abusers (Luke 6:28). Instead of quick, unfair judgment, their words will be filled with mercy (Luke 6:36–37). And they will gently lead others away from their sin and toward Christ (Luke 6:42).
Matthew includes a similar statement from Jesus as well as His additional sober warning: "I tell you, on the day of judgment people will give account for every careless word they speak, for by your words you will be justified, and by your words you will be condemned" (Matthew 12:36–37). Our words will either show that we are truly Christ-followers or reflect the evil in our hearts. In Matthew's context, Jesus says this after the Pharisees accuse Jesus of using the power of Satan to perform miracles. Their hearts are hardened against Jesus and their words, which blaspheme the Holy Spirit, prove it (Matthew 12:22–37).
Jesus has already mentioned that the Father (Luke 6:36) inspires goodness. Next, He explains that goodness is produced by obeying Jesus' words. Obedience to Him is like building a house on a rock; it remains steady no matter what storms come. In the same way, building our lives on His commands will ensure we will not become overwhelmed when faced with the storms of life (Luke 6:46–49).