The differentiation between the jurisdictions of Christ and the temporal authority does not limit Christian activity to the spiritual sphere alone, but dictates the manner in which the Christian wields the sword and obeys temporal authority. Turning to the Biblical passages in question, Luther argues that Christ’s words in Matthew 5 should be interpreted to mean that the temporal sword not be used among Christians, that the means of rule of the kingdom of the world should not be allowed to rule the kingdom of Christ. Luther writes that, “For [Christ] is a king over Christians and rules by the Holy Spirit alone, without law. Although he sanctions the sword, he did not make use of it, for it serves no purpose in his kingdom, in which there are none but the upright.” Matthew 5 thus prohibits the use of the temporal sword within the kingdom of Christ, but does not explicitly forbid the Christian to serve and obey those who wield the sword. Because Christians do not simply live on their own, but live in community with their neighbors, who are often not Christians, they must submit to the temporal law, not for their own sake, but for that of their neighbor.
Luther, considering Romans and I Peter, says that, “Because the sword is most beneficial and necessary for the world whole in order to preserve peace, punish sin, and restrain the wicked, the Christian submits most willingly to the rule of the sword, pays his taxes, honors those in authority, serves, helps, and does all he can to assist the governing authority, that it may continue to function and be held in honor and fear. Although he has no need of these things for himself –to him they are not essential – nevertheless, he concerns himself about what is serviceable and of benefit to others…” This position addresses the question of why a Christian submits to temporal authority when he belongs to the kingdom of God; “Just as he [the Christian] performs all other works of love which he himself does not need… so he serves the governing authority not because he needs it but for the sake of others, that they may be protected and that the wicked may not become worse.” Thus Christians obey not for their own sake, but for love of their neighbors.
May a Christian then bear the temporal sword and punish the wicked out of love for his neighbor? This question must be asked with regard to both the use of the sword in vocational application (Can Christians be soldiers or magistrates?), as well as in a practically specific sense (Can I use the sword to defend my neighbor against so and so?). For Luther, the Christian remains under an “obligation to serve and assist the sword by whatever means you can, with body, goods, honor, and soul….” He admonishes Christians to fulfill the duties and offices of temporal authority if a need arises, that “the essential governmental authority may not be despised and become enfeebled or perish.” Luther believes that Christians can bear the sword in service to one’s neighbor and that by doing so the Christian may simultaneously suffer injustice and evil as well as punish injustice and evil in the name of love for their neighbor. “For love pervades all and transcends all, it considers only what is necessary and beneficial to others, and does not ask whether it is old or new… where you see that your neighbor needs it, there love constrains you to do as a matter of necessity that which would otherwise be optional and not necessary for you either to do or to leave undone.” Since the New Testament portrays the office of soldier as godly, and “since Paul says here [Romans 13] that the governing authority is God’s servant, we must allow it to be exercised not only by the heathen but by all men.” Thus, a Christian should not resist evil when it concerns himself, but “on behalf others, however, he may and should seek vengeance, justice, protection, and help, and do as much as he can to achieve it. Likewise, the governing authority should, on its own initiative or through the instigation of others, help and protect him too, without any complaint, application, or instigation on his own part.” Christ’s words thereby intensify the proper form of action for Christians, who must simultaneously be willing to allow themselves to be taken advantage of, while seeking justice for all others because of their love of neighbors.
Luther thus explains his interpretation of Matthew 5, Romans 13, and I Peter 2 using the construction of the two kingdoms, the kingdom of Christ and the kingdom of the world. Christians should never within the context of the kingdom of Christ wield the sword or utilize the power of temporal authority. They are, however, bound to obey secular authorities, not for their own sake, but because their love of neighbor motivates them. Within the parameters of obeying the laws of temporal authority and love of neighbor, the Christian may be called to fulfill the office of magistrate, judge, soldier, or some other temporal ruler, and thus wield the sword in the manner appropriate for such positions of temporal authority. This power Christians must never invoke on their own behalf, but only out of love for one’s neighbor. Luther thus argues that Christians, by virtue of love for their neighbors, must never wield the sword in any capacity within the kingdom of Christ, though they should be willing to fulfill positions of temporal authority and wield the sword to restrain wickedness on behalf of others. Within this understanding of Luther’s two kingdom doctrine, it now becomes difficult to warrant Christian inaction on behalf of one’s neighbor.
 On Temporal Authority, 93.  Ibid., 94.  Ibid., 94.  Ibid., 95.  Ibid., 95.  Ibid., 98.  Ibid., 99-100.  Ibid., 101.  For Luther, Christians should act selflessly, though within a community that willingly will act on their behalf. Thus acting selflessly actually carries an expectation of assistance from others. Whether such action ought to be considered truly selfless for the Christian remains a matter of consideration, though not one that we will address.