To German pastor and theologian and martyr, Dietrich Bonhoeffer, practicing the Sermon on the Mount in Matthew 5-7 was essential to be a disciple of Jesus.  The editors in the Cost of Discipleship put it this way…

Bonhoeffer’s emphasis on the obedient deeds of discipleship in response to God’s word in Jesus Christ is in his view a restoration of the meaning of faith in a world that has become increasingly bereft of compassion, peace, forgiveness of enemies, purity of heart, and meekness, yet increasingly willing to exploit the poor and oppress those who struggle for justice.

In short, the perspective of the Beatitudes of Jesus’ Sermon on the Mount quickly became Bonhoeffer’s way of elucidating the meaning of discipleship for Christians and their churches.  if, in a nation that has turned away from Christianity, faith is ever to be restored, the church must preach again what is central in the Christian faith, the call of Jesus Christ to follow him (Quoted in Stephen R. Haynes and Lori Brandt Hale, Bonhoeffer for Armchair Theologians, 98-99).