“Cheap grace is grace without discipleship, grace without the cross, grace without Jesus Christ, living and incarnate.
Costly grace, Biblical grace, is the treasure hidden in the field; for the sake of it a man will gladly go and sell all that he has. It is the pearl of great price to buy which the merchant will sell all his goods. It is the kingly rule of Christ, for whose sake a man will pluck out the eye which causes him to stumble. It is the call of Jesus Christ at which the disciple leaves his nets and follows him.” – Bonhoeffer, The Cost of Discipleship