well sure, most people believe that god is completely sovereign, so everything that happens is his will. So having the government right now is his will. But that doesn't mean that it is not his will for it to end in the future. Just because slavery was an institution at one point doesn't mean it was his will for it to continue. Actually from the standpoint of absolute sovereignty it was his will that it should end, when it did, and exactly how it did
RE: Can a Christian be an Anarchist? (Part 1)