"We Christians are above all addressed by the command of love to the point that we ourselves must live in peace with every person, just like Christ when he preached peace to the community, exemplified in peace with one's brother and sister, with one's neighbor, with the Samaritan. Unless we have this peace, we cannot preach peace to people.
Most who are annoyed at the world of peace among peoples, moreover, are already calling in question the love of enemies over against personal enemy. When we wish to speak about the conditions for peace, therefore, we would do well always to keep before our eyes the fact that relationships between two nations bear close analogy to relationships between two individuals.
The conditions that are opposed to peace are in the one as in the other relationship: lust for power, pride, inordinate desire for glory and honor, arrogance, feelings of inferiority, and strife over more living space and over one's 'bread' or life.
What is sin for an individual is never virtue for an entire people or nation. What is proclaimed as the gospel to the church, the congregation, and, thereby, the individual Christian, is spoken to the world as a judgment. When a people refuses to hear this command, then Christians are called forth from that people to give witness to peace.
Let us take care, however, that we proclaim peace from a spirit of love and not from any zeal for security or from any mere political aim."
- Dietrich Bonhoeffer, A Testament to Freedom, 95