'To follow Jesus means self-renunciation and absolute adherence to him, and therefore a will dominated by lust can never be allowed to do what it likes. Even momentary desire is a barrier to the following of Jesus, and brings the whole body into hell, making us sell our heavenly birthright for a mess of pottage, and showing that we lack faith in him who will reward mortification with joy a hundredfold. Instead of trusting to the unseen, we prefer the tangible fruits of desire, and so we fall from the path of discipleship and lose touch with Jesus. Lust is impure because it is unbelief, and therefore it is to be shunned. No sacrifice is too great if it enables us to conquer a lust which cuts us off from Jesus.'
Dietrich Bonhoeffer, The Cost of Discipleship, p.83.