What does the Bible say about the mystery of the kingdom of God?

In Mark 4:1-20, the mystery of the kingdom of God is presented through the parable of the sower. Jesus explains that the word of God is sown among various types of soil, symbolizing different responses to His message. He notes that only those given ears to hear—that is, the elect—truly understand the kingdom's mysteries, underscoring God's sovereign choice in revealing truth to His people while concealing it from others. This passage emphasizes the grace of God in granting understanding to some, while the rest are left in spiritual blindness, fulfilling God's purpose.