“You will be clean in God’s eyes and in the eyes of the nation” (Numbers 32:22). The Jewish nation is about to enter the Land of Israel and two of the 12 tribes seem to want to avoid their responsibility to join their brethren in the battle for the land.
Moses emphasizes to them that there is both a religious and moral obligation to be involved in the war. On the religious side, the Land of Israel is given to the Jewish people as a heritage — something that they are commanded to fight for and treasure, ensuring that it is always there for future generations. Furthermore, they have a moral obligation to join with their brothers in battle, for choosing not to do so would affect the morale of the nation.
It seems that the Torah may be telling us that we can’t be committed to God without being committed to both Israel and the Jewish nation. To only profess the spiritual, Godly aspects of religion without the social, moral side is not what the Torah is about. In the words of King David, who spent much of his life fighting on behalf of Israel, “May the Lord bless His nation with peace.”