Costly grace is the gospel which must be sought again and again and again, the gift which must be asked for, the door at which a man must knock. Such grace is costly because it calls us to follow, and it is grace because it calls us to follow Jesus Christ. It is costly because it costs a man his life, and it is grace because it gives a man the only true life. It is costly because it condemns sin, and grace because it justifies the sinner. Above all, it is costly because it cost God the life of his Son: ‘Ye were bought at a price’, and what has cost God much cannot be cheap for us. Above all, it is grace because God did not reckon his Son too dear a price to pay for our life, but delivered him up for us. Costly grace is the Incarnation of God.
-Dietrich Bonhoeffer, The Cost of Discipleship
Dietrich Bonhoeffer (1906 – 1945) was a German Lutheran pastor, theologian, anti-Nazi resistant and ultimately martyr to the gospel. The historical events leading up to WWII led him to write especially on the topic of discipleship, as proclaiming Christians failed to denounce the direction which the German church was headed in. His work remains a prophetic voice for today, calling us to a life fully-devoted to Christ and his cause.