Thanks to Melissa for sending this gem from Karl Barth my way:
If along the third main line of the texts in question we have to do with the overcoming, proclaimed with the incursion of the kingdom of God, of the false separation between man and man revealed in the friend-foe relationship and concretely expressing itself in the exercise of force, along a fourth line we have, conversely, the dissolution of self-evident attachments between man and man. It is a matter of what in popular usage, although not in that of the Bible, is usually described as the family. The relationships between husband and wife, parents and children, brothers and sisters, etc., are not questioned as such. Man would not be man if he did not stand in these relationships. What is questioned is the impulsive intensity with which he allows himself to be enfolded by, and thinks that he himself should enfold, those who stand to him in these relationships. What is questioned is his self-sufficiency in the warmth of these relationships, the resolving of their problems and the sphere of their joys and sorrows. What is questioned is his imprisonment in them, in which he is no less a captive than in other respects he may be to possessions or fame. The message of liberation comes to him in this captivity to the clan. Thus the excuse of the invited guest: ” I have married a wife, and therefore I cannot come ” (Lk. 14:20), is seen to be on exactly the same level as those of others who had bought land or oxen which claimed their prior interest. And in the same connection Jesus gives the remarkable reply to the man who was ready to be a disciple but first wanted to bury his father: ” Let the dead bury their dead but go thou and preach the kingdom of God ” (Lk. 9:59f.). To the same series belong all the provocative sayings of Jesus about the leaving (apheinai), dividing (dichazein), disuniting (diamerizein) and even hating (misein) which are involved in the discipleship of Jesus – not destroying the relationships as such, but certainly dissolving the connections which continually arise and obtain in them. According to Mk, 10:29 we have not only to leave house and lands but even brother or sister, mother or father or children (the ” or ” shows us that we are dealing with individual cases), for His sake and for the sake of the Gospel. Jesus also warns us against the view that He has come to bring peace on earth (Mt. 10:34f.). He has not come to bring peace, but a sword. And if a man loves father or mother, son or daughter, more than Him, he is not worthy of Him. Or, according to the parallel passage in Lk. 12:52 : ” For from henceforth there shall be five in one house divided, three against two, and two against three.” The strangest possible expression is used in Lk. 14:26 : ” If any man come to me, and hate not his father, and mother, and wife, and children, and brethren, and sisters, yea, and his own life also, he cannot be my disciple.” Hate ? It is not the persons that are to be hated, for why should they be excluded from the command to love our neighbors ? It is the hold which these persons have and by which they themselves are also gripped. It is the concentration of neighborly love on these persons, which really means its denial. It is the indolent peace of a clannish warmth in relation to these persons, with its necessary implication of cold war against all others. The coming of the kingdom of God means an end of the absolute of family no less than that of possession and fame. Again, there is no general rule. No new law has been set up in competition with that of the world, which points so powerfully in the opposite direction. But there is proclaimed the freedom of the disciple from the general law as it is given to him, and has to be exercised by him, in a particular situation (by the particular direction which he receives). There can be no doubt that in its fear of the bogy of monasticism Protestantism has very radically ignored this proclamation of Jesus Christ, as also that of other freedoms. To a very large extent it has acted as though Jesus had done the very opposite and proclaimed this attachment – the absolute of family. Can we really imagine a single one of the prophets or apostles in the role of the happy father, or grandfather, or even uncle, as it has found self-evident sanctification in the famous Evangelical parsonage or manse ? They may well have occupied this role. But in the function in which they are seen by us they stand outside these connections. In this respect, too, no one is asked to undertake arbitrary adventures. But again, no one who really regards himself as called by Jesus to discipleship can evade the question whether he might not be asked for inner and outer obedience along these lines. The life of the new creature is something rather different from a healthy and worthy continuation of the old. When the order is given to express this, we must not refuse it an obedience which is no less concrete than the command.
~ Karl Barth, CD IV/2 549-550