The Mystery of the Kingdom
The mystery of the kingdom is unique among all the New Testament mysteries for one reason: it comes from the lips of Jesus Himself. In the Synoptic Gospels — Matthew, Mark, and Luke — Jesus tells His disciples that they have been given the mystery (or mysteries) of the kingdom. It is the only recorded instance of Jesus using the word mystērion.
The Key Passage: Mark 4:10-12
"And when he was alone, those around him with the twelve asked him about the parables. And he said to them, 'To you has been given the mystery of the kingdom of God, but for those outside everything is in parables, so that they may indeed see but not perceive, and may indeed hear but not understand, lest they should turn and be forgiven.'"— Mark 4:10-12 (ESV)
The parallel accounts appear in Matthew 13:11 (which uses the plural "mysteries of the kingdom of heaven") and Luke 8:10 ("the mysteries of the kingdom of God"). See Did Jesus Use the Word Mystery? for a discussion of why this is Jesus' only use of the term.
What Is the Mystery of the Kingdom?
Jesus does not define the mystery in the way Paul often does. He does not say "the mystery is X." Instead, He links the mystery to the parables themselves and to the capacity of the hearer to understand. The disciples are "given" the mystery; those outside receive everything in parable form. This suggests that the mystery of the kingdom is not a single doctrinal proposition but a way of perceiving reality — an insight into how God's kingdom operates.
In context, Jesus has just told the parable of the sower (Mark 4:1-9), which describes different responses to the word of God. The "mystery" may be this: that the kingdom of God is present and active in the world, but it does not arrive with overwhelming visible power. It arrives like seed scattered on soil — hidden, gradual, dependent on reception. The kingdom is "already but not yet," and recognizing this requires divine illumination.
Parables as Mystery-Bearers
Jesus' use of parables is itself an expression of the mystery concept. Parables simultaneously reveal and conceal. For those with ears to hear, they illuminate the nature of God's kingdom. For those without, they remain opaque. This dual function mirrors the structure of mystērion throughout the New Testament: a truth that is available but not obvious, revealed to some and hidden from others.
The Difficult Saying: "So That"
Mark 4:12 is one of the most challenging sayings in the Gospels. Jesus appears to say that He teaches in parables in order that outsiders will not understand. The Greek word hina ("so that") has been debated for centuries. Some interpreters soften it to "with the result that" (a weakened sense of hina attested elsewhere in Greek), while others take it at face value as an expression of divine judgment. Matthew's parallel (13:13) uses "because" (hoti) rather than "so that," which suggests a slightly different emphasis.
This difficulty is itself part of the mystery. The passage resists easy explanation, which is fitting for a text about the hiddenness and revelation of divine truth.
Connection to Paul
Although Paul never directly quotes Mark 4:11, his entire theology of mystery builds on the foundation that Jesus laid here. The idea that divine truth is given by revelation, that it is not accessible to mere human effort, and that it requires a change in the hearer — all of these themes in Paul's letters echo Jesus' parable discourse. Paul and the Mystery of God explores this development in detail.