What does Matthew 13:15 mean?
A prophecy found in Isaiah 6:8–10 features God passing along these words. Jesus applies Isaiah's words to the Israelites of His own generation. He says that the hearts of the people have grown dull. They can barely hear with their ears, and their eyes are closed. Why? They don't want to see or hear or understand, because then they would need to repent.In prior verses, Jesus has indicated that He's deliberately teaching in parables in order to partially obscure the truth from the crowds. Prophecies such as this show why this is an act of judgment, not an unfair trick. The people's refusal to believe comes first, and in response, God amplifies their stubbornness. Those who are sincere can, and will, still hear the message and accept it. But most will not (Matthew 7:13–14).
Both Isaiah and Jesus are explaining two primary messages. First, the people, including the religious leaders, have refused to believe that Jesus is the Messiah despite hearing His words and seeing His miracles. Second, and for that reason, God has ensured they will not believe now despite hearing Jesus teach in parables and seeing further miracles. The people are responsible for refusing to understand what is obvious, and, as a result, God has acted to keep them from understanding in the future (Proverbs 29:1).