Before Bonhoeffer could challenge his readers, he had to convince them to "get on his bandwagon". He begins by writing about grace. Bonhoeffer categorizes grace into two groups: one is cheap grace and the other is costly grace. To Bonhoeffer, cheap grace is the denial of the living Word of God and the justification of sin without the justification of the sinner. He goes so far as to say, "Cheap grace is the preaching of forgiveness without requiring repentance, baptism without church discipline, Communion without confession, absolution without personal confession" (p. 44). Bonhoeffer even goes as far as to say that cheap grace is another word for damnation. Obviously, he isn't advocating this type of grace. The grace Bonhoeffer longs for Christians to have is costly grace. This type of grace requires action of the Christian. "Costly grace is the gospel which must be sought again and again..." (p. 45). Bonhoeffer states that since we are called to follow it, it is costly, and because we are called to follow Christ, it is grace. "Above all, it is costly because it cost God the life of his Son..." (p.45). Any Christian with any conviction to follow Christ is almost forced to agree with Bonhoeffer, and that is exactly what he wanted. Now that you're "on the bandwagon", he can hit you with his radical ideas of what it means to follow Christ.
Now that Bonhoeffer has you, he says to just obey God, don't rationalize. We should not question God; we should just do as He says. He also points out that following God isn't a cakewalk. Discipleship means suffering, and we should not kid ourselves by believing otherwise.
Bonhoeffer then shifts to show us how we should follow Christ. He does so by thoroughly covering the Sermon on the Mount. He doesn't beat around the bush here. He is very straightforward in conveying his ideas. In this section, Bonhoeffer makes the claim that disciples should not dream of progress, or power and of the future; rather, we should meditate on the end and the coming kingdom. He emphasizes that true disciples show by every word and gesture that they are not of this world.
Bonhoeffer also discusses the issues of being visible for the world to see and the righteousness of Christ. He says, although I do not agree, that we should still adhere to the original law of the Old Testament. Bonhoeffer also denounces lust, as this would interfere with our "absolute adherence to him" (p. 131).
Bonhoeffer also makes an excellent exposition on revenge. He says, "The right way to requite evil, according to Jesus, is not to resist it" (p. 141). Instead of being overcome by evil, we should let evil run its course, and let it run itself out so no further evil can be done. He supports this by stating that Jesus died when he didn't have to. He could've easily avoided the whole situation, but he put up with a lot of evil when he could've taken himself out of this world with only a thought. He didn't resist the evil given to him; he accepted it willingly.
Then Bonhoeffer hits his readers with a difficult part of Christianity: "Love your enemies", "Bless them that persecute you", Do good to them that hate you", Pray for them which despitefully use you and persecute you". This is related to his discussion on revenge. Instead of returning hate to those who hate us, we should return love.
Bonhoeffer then discusses messengers of the Gospel. He talks about how they are called, what they do, and what kind of persecution they receive for following God. He does end this section on a good note; he discusses the reward for being faithful to God, "...indeed forgiveness and salvation, life and bliss" (p. 220).
Bonhoeffer concludes by describing what the church of Christ should be. He discusses baptism. He writes what our churches and we as believers should be like, also.
I thought The Cost of Discipleship was a very challenging book to say the least. I didn't know what to expect when I started...