Some snippets from Appendix 2 of Dallas Willard’s ‘The Spirit of the Disciplines’:

“The word ‘disciple’ occurs 269 times in the New Testament. ‘Christian’ is found only 3 times and was first introduced to refer precisely to the disciples. . . . For the last several decades our churches have not made discipleship a condition of being a Christian. One is not required to be, or to intend to be, a disciple in order to become a Christian, and one may remain a Christian without any signs of progress toward or in discipleship. . . .So far as the churches of our day are concerned, discipleship is clearly optional. . . In 1937 Dietrich Bonhoeffer gave the world his book The Cost Of Discipleship. It was a masterful attack on “easy Christianity”. . . But the cost of nondiscipleship is far greater. . . Nondiscipleship costs abiding peace, a life penetrated throughout by love, faith that sees everything in the light of God’s overriding purposes for good, hopefulness that stands firm in the most discouraging of circumstances, power to do what is right and withstand the forces of evil. In short, it costs exactly that abundance of life that Jesus said he came to bring (John 10:10).”