"Jesus is not saying that you can earn the kingdom of heaven by the thoroughness of your commitment. Your willingness to sell everything ... is the way you receive the kingdom of heaven, but it's not the way to merit the kingdom of heaven. That's very important.
You turn the light switch on on the wall, and it seems to cause the coming on of the light, but it doesn't. As we know, what causes the coming on of the light is the power. The light switch simply is a channel to the power ... the light switch has no power of its own.
This is one of the most important distinctions not only in theology but in your own personal experiential understanding of Christianity. There is something God says that you must do to receive the kingdom of heaven, but there's nothing you can do to earn the kingdom of heaven. Total commitment is the way it is received but not earned. The Parable of the Prodigal Son tells us how it is earned because, you see, to get the robe, to get the ring, to get the fatted calf, though it's free to the prodigal us, the prodigal you and me, it's at the expense of the older brother; it's been paid for by someone else. And now, of course, it's received through repentance, through commitment, through the willingness of the prodigal son to come and say, "Father, do what you want with me. Father, no conditions. Father, I come back and I throw myself at your feet." What is going on? Repentance, commitment, letting go of everything, laying yourself out, utter commitment. But that is not what brings him back in. That's what receives the father's welcome, but what earns the father's welcome ... is the fact that all of the wealth the father puts now onto the prodigal—the robe, the ring, and the fatted cow—belongs to the elder brother, so it's at his expense."
Tim Keller, The Parable of the Pearl: On Priorities, sermon at Redeemer Presbyterian Church of NYC on August 28, 1994. A sermon on Jesus's parables of the hidden treasure and the pearl from Matthew 13:44–45.
"Imagine yourself as a living house. God comes in to rebuild that house. At first, perhaps, you can understand what he is doing. He is getting the drains right and stopping the leaks in the roof and so on; you knew that those jobs needed doing and so you are not surprised. But presently he starts knocking the house about in a way that hurts abominably and does not seem to make any sense. What on earth is he up to? The explanation is that he is building quite a different house from the one you thought of—throwing out a new wing here, putting on an extra floor there, running up towers, making courtyards. You thought you were being made into a decent little cottage, but he is building a palace. He intends to come and live in it himself."
C.S. Lewis, Mere Christianity