Our Lord’s teaching can be summed up in this: the relationship that He demands for us is an impossible one unless He has done a supernatural work in us. Jesus Christ demands that His disciple does not allow even the slightest trace of resentment in his heart when faced with tyranny and injustice. No amount of enthusiasm will ever stand up to the strain that Jesus Christ will put upon His servant. Only one thing will bear the strain, and that is a personal relationship with Jesus Christ Himself— a relationship that has been examined, purified, and tested until only one purpose remains and I can truly say, “I am here for God to send me where He will.” Everything else may become blurred, but this relationship with Jesus Christ must never be.
The Sermon on the Mount is not some unattainable goal; it is a statement of what will happen in me when Jesus Christ has changed my nature by putting His own nature in me. Jesus Christ is the only One who can fulfill the Sermon on the Mount.
If we are to be disciples of Jesus, we must be made disciples supernaturally. And as long as we consciously maintain the determined purpose to be His disciples, we can be sure that we are not disciples. Jesus says, “You did not choose Me, but I chose you…” (John 15:16). That is the way the grace of God begins. It is a constraint we can never escape; we can disobey it, but we can never start it or produce it ourselves. We are drawn to God by a work of His supernatural grace, and we can never trace back to find where the work began. Our Lord’s making of a disciple is supernatural. He does not build on any natural capacity of ours at all. God does not ask us to do the things that are naturally easy for us— He only asks us to do the things that we are perfectly fit to do through His grace, and that is where the cross we must bear will always come.