For instance, it was once a recognized principle in the laws of nations, that, if a merchant vessel were wrecked on a foreign coast, the wreck became the property of the occupants of the coast, although the real owners were living. It was an established principle also, not less unjust, that, if a person, resident in a foreign country, died there, his property, instead of descending to those whom he designed and wished to be his heirs, should be taken for the use and benefit of the country where he happened to be resident at the time of his death. It was also originally one of the laws of war, which make a part of the existing laws of nations, that the prisoners taken in the progress of a contest might be put to death. The conqueror was regarded as possessing complete power over the captured; so that he could take away their lives if he supposed their death would turn to more account than their preservation. But, in these and in a number of other respects, the code of nations has been very much improved. A more benevolent spirit now pervades it. But still, it must be admitted, that it is far from being what it should be.
Now, it may not be the duty of all Christians to labor directly for the improvement of the code of nations, because Providence may not give to all the power and the opportunity to do so; but it belongs to Christianity, it is a part of the results of the Christian system, not only to improve, but to perfect it. Christianity operating from the center to the circumference, contemplates universal advancement. It raises all, — and raises all at the same time; — not only the individual, but the family, the state, and the whole world as it is united together by the international code.
Every man, therefore, who fully possesses the Christian spirit, and whom Providence permits to labor in that direction, will bear his part in this great work. His relations to God are such that he will necessarily contribute that mite or talent, whatever it may be, which is appropriate to his personal ability, and his position in the social arrangement. His first work is to perfect his own nature; or rather, to let God do it, by leaving himself is the hands of the divine operator. But in being perfected in himself, he is perfected at the same time in the relations he sustains to others. In being a better man, he is not only a better father and husband, but a better citizen; — and while he labors and prays for the new and perfected life of those immediately around him, he does what he can for the restoration of all others in all places.
— edited from A Treatise on Divine Union (1851) Part 7, Chapter 7.