Chapter 10 of 32 · Part II — The Sermon on the Mount

Woman

As with murder, Jesus locates adultery in desire itself, before any act — and ties the whole discussion back to the disciple's body belonging to Christ.

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    At a glance

    The lustful glance

    A desire that never becomes an act still counts, in Jesus' reckoning, as already having crossed the line — there is no safely private compartment for it.

    Bonhoeffer's grounding

    Because the disciple's body belongs to Christ's own body, sexual sin is not merely a private moral lapse; it is a wound against the fellowship the disciple shares with Christ and the church.

    The chapter heading text (KJV)

    “Ye have heard that it was said by them of old time, Thou shalt not commit adultery: But I say unto you, That whosoever looketh on a woman to lust after her hath committed adultery with her already in his heart… It hath been said, Whosoever shall put away his wife, let him give her a writing of divorcement: But I say unto you, That whosoever shall put away his wife, saving for the cause of fornication, causeth her to commit adultery.”

    Matthew 5:27–32 KJV

    Summary

    Bonhoeffer reads this section as a continuation of the previous chapter's logic: just as the command against murder is traced back to contemptuous anger, the command against adultery is traced back to lust, so that an entirely interior desire is shown to already carry the moral weight of the act it anticipates. There is no protected inner space where desire can be indulged as long as it stays private; Jesus dissolves the distinction between the secret heart and the visible deed.

    He roots the seriousness of this in Paul's teaching that the believer's body is a member of Christ's own body, so that even bodily sin is never merely personal. Sexual desire detached from self-control is described as idolatry — the desiring self setting up its own satisfaction as the thing ultimately served, in place of God. This is why Bonhoeffer treats the demand for radical self-renunciation (the vivid language of plucking out an offending eye) as entirely proportionate rather than extreme: nothing less addresses a sin that reaches the root of who a person serves.

    On divorce, Bonhoeffer reads Jesus as protecting the seriousness of marriage from a legal culture that had turned the certificate of divorce into a convenient escape hatch. What matters is not the technical legality of the arrangement but the reality it either honours or betrays — marriage as a real, binding union, not a contract dissolved at will and then quietly rationalised as blameless because the paperwork was in order.

    Throughout, Bonhoeffer keeps returning to the disciples' bodies as already crucified with Christ, sharing in his death to sin, which is what gives them the strength for the chastity being demanded rather than leaving it as an impossible external rule. The chapter's brevity mirrors its content: having established the principle — the body belongs to Christ, not to its own desire — he lets it stand rather than working through every case, trusting the disciple community to apply it.

    Key points

    • Jesus locates adultery in desire itself, dissolving any protected inner space where lust could be indulged as long as it never becomes an act.
    • Bonhoeffer roots this in Paul's teaching that the believer's body belongs to Christ's body — sexual sin is never merely a private, victimless matter.
    • Desire detached from self-control is treated as a form of idolatry: serving one's own satisfaction rather than God.
    • On divorce, Jesus is read as defending the reality and seriousness of marriage against a legal culture that had reduced it to paperwork.
    • The disciples' capacity for chastity comes from already sharing, bodily, in Christ's death to sin — not from willpower applied to an external rule.

    Related Scripture

    • 1 Corinthians 6:15–20
    • Job 31:1
    • Malachi 2:14–16
    • Galatians 5:24

    For reflection and discussion

    1. Bonhoeffer says there is no private compartment for desire safely separate from action. Where does that challenge how you have thought about your own inner life?
    2. How does thinking of your body as ‘a member of Christ’ change how you weigh decisions that might seem to affect no one but yourself?
    3. Where might you be treating a serious commitment — not necessarily marriage — more like a revocable arrangement than the binding reality Bonhoeffer says Jesus is defending?

    These notes are an original UECF.NET study companion and are not a reproduction of Bonhoeffer's text, which remains in copyright. Read chapter 10 — book pages 147–150 — in The Cost of Discipleship by Dietrich Bonhoeffer (Macmillan / SCM Press, Revised and Unabridged Edition). Scripture quotations above are the King James Version.

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