"The command of the Commander is a permission, and in this it is fundamentally and finally different from all other commands.
It cannot be said of any other commands in themselves and as such that they are permissions, releases, liberations; that they give us freedom. On the contrary, their commanding is in every respect a holding fast, a binding, a fettering. Each of them constitutes one of the many powers and dominions and authorities which restrict the freedom of man, which, under the pretense of their own divinity and in the supposed best interests of man, are not at all willing to allow him to go his own ways happily and peacefully. They all mean that at some point man is interrupted and even jostled; that at some point -- and worst of all when he begins to command himself -- he is vexed and tormented. In one form or another they all express to man the suspicion that it might be dangerous to free him, that he would certainly misuse his liberty, that once liberated, he would only create trouble for himself and others. From the most varied angles, they fill him with anxious fears: the intellectual fear of spiritual isolation; fear of the possibility of a world food shortage; a moral fear of his own possibilities; political fear in the face of his own weakness. They use these fears to appeal to him, instilling them into him and holding him in their grip. In essence, their bidding is a forbidding; the refusal of all possible permissions. This is what distinguishes the sphere of these commands very sharply from that of the command of God. Commands which are only ostensibly and allegedly divine, and misunderstandings of the real command of God, always betray themselves by the fact that they create and restore and maintain this sphere of distrust and fear.
The command of God sets man free. The command of God permits. It is only in this way that it commands. It permits even though it always has in concreto the form of one of the other commands, even though it, too, says, "Thou shalt" and "Thou shalt not," even though it stands before man, warning, disturbing, restraining, binding and committing. The command of God and other commands do the same thing, but it is not really the same. No matter in what guise the command of God meets us, in accordance with its basis and context, it will always set us free along a definite line. It will not compel man, but burst open the door of the compulsion under which he has been living. It will not meet him with mistrust but with trust. It will not appeal to his fear but to his courage. It will instill courage, and not fear into him. This is the case because the command, as we have seen, is itself the form of the grace of God, the intervention of the God who has taken the curse from us to draw us to Himself -- the easy yoke and the light burden of Christ, which as such are not to be exchanged for any other yoke or burden, and the assumption of which is in every sense our quickening and refreshing. This is what God prepares for us when He gives us His command. The man who stands under the jurisdiction of all those other commands of God and is not refreshed is not the obedient man but the man who disobeys God, who, instead of living according to the determination of the image of God, and therefore in conformity with the grace of God, has succumbed to the temptation to eat of the tree of the knowledge of good and evil, which is forbidden him for his own good, and in this way to exalt himself to a spurious divine likeness." Karl Barth, CD II/2, 585-6
This is why, when situated properly before God, with fellow humanity, and among all created life, the command to human beings is vocatio. If you have come to discern such a vocation, a call from God toward, you know that obedience is hard enough under the gospel. Hard enough without the imposition of other commands, especially those which are misunderstandings of the command of God. Especially those which would use a theology of orders to bind you, not only from yourself, but from God's calling. This is why you have only one obedience, and I love the Roman use of that term for what we so bureaucratically call "assignment".