The kingdom of heaven is like treasure hidden in a field, which a man found and covered up. Then in his joy he goes and sells all that he has and buys that field. (Matt 13:44, ESV)
This parable, which is well-known, I will cover fairly briefly: many authors have written a great deal on the subject, so my thoughts are worth little in this case.
The implied background of this passage is that someone buried a treasure and died, so that it is no longer his to own. The current landowner, it appears, does not know about the treasure. So let me ask…what kind of person can just “find” a hidden treasure in a landowner’s field, at the time of Christ?
There surely can be only one answer: a farmhand was plowing the fields for his master when he discovers the treasure. So now he is faced with three choices: he can simply steal the treasure; he can inform his master; or he can sell everything he has and legally buy the land (and the treasure hidden within).
Because he is (presumably) a moral man, he does not steal the treasure. So now he is left with two choices: will he be willing to lose everything in order to gain something of greater value? Is he willing to take the risk that his master will not sell the land to him? He decides to take that risk, and is rewarded with hitting the ancient Jewish version of the lottery.
The key lesson here, as all commentators will point out, is that the man is shown this amazing reward—but he cannot get it unless he takes a large risk. He must give up everything he owns in order to buy the land so that he can legally have the treasure.
Jesus here is comparing our salvation to this treasure. If we wish to gain the kingdom of God, it comes at a big price: we must give up ownership of our own lives; we must love Him more than the world; we must stop storing treasures up here on earth; we must trust in His guidance rather than human wisdom; we must face ridicule; we must face persecution; we must face suffering; we may even face death. Are we ready to make such a sacrifice to purchase something of everlasting value?