The expansion that the Bible talks about is spiritual, not political. If it results in political change, it would do so only indirectly. As the gospel expands to influence more people in more levels of society, then those people would naturally favor policies that are biblical. But the expansion is explicitly spiritual — it refers to a pervasiveness of spiritual ideas and powers, including miraculous powers. To directly focus on the political is to commit the very thing that Jesus condemned — “for you care about the things of men, and not the things of God.” The Christian obsession with politics is a natural lust, an idol, and a replacement for the promise of power in the gospel, which the spiritually feeble and wayward have rejected because of unbelief.
As for expansionism in the context of the cessationism vs. continuationism debate, my position is that both are wrong, or at least the latter is too weak and misleading. Cessationism is an outright rejection of the gospel. Continuationism is much better; however, because it allows the anti-gospel group to define the terms of the doctrine, it is also a compromise of the gospel. It also neglects the fact that Jesus commanded extreme exponential expansion, not mere continuation. The gospel doctrine is that the miraculous works of Christ should be performed by more kinds of believers, by more multitudes of believers, in more geographical areas, and that this power should increase from generation to generation. Cessationism condemns this essential gospel principle. Continuationism is completely inadequate to represent this. Continuationism is so very lame compared to what the gospel actually teaches.
You asked how we would relate this nonnegotiable pillar of the gospel to the school of thought that wishes to apply God’s law to reconstruct society. The answer is that anyone who adheres to such a school of thought, but who is a cessationist, is also a liar and a hypocrite. If one wishes to reconstruct society with the law of God, he must do it with the gospel, and the gospel is as I stated above — expanding the participation and magnitude of the saving message and miracle power of God in the name of Jesus Christ. Like any cessationist, the cessationist who wishes to reconstruct society is not interested in extending Christ’s kingdom, but in enforcing his own personal philosophy about the proper operation of society. He seeks to mold society in his own image — perhaps a conservative political philosophy labeled “Christian” — but not anything like the image of Christ.
As Jesus said, “Go and tell John what you have seen and heard: the blind receive their sight, the lame walk, lepers are cleansed, and the deaf hear, the dead are raised up, the poor have good news preached to them. And blessed is the one who is not offended by me.” In other words, Jesus preached the gospel, and healed the sick, healed the sick, healed the sick, healed the sick, and healed the sick. Multitudes of Christians are offended by such a Jesus. They want a political Christ to save America, to save China, or some such thing. But the only Jesus is one who preaches, and then heals, and heals, and heals, and heals, and heals with miracles. This is the only Jesus, and the only gospel. If you do not want this Jesus, there is no other, and you cannot be saved, let alone reshape society! If you want to save America or any other place, preach the gospel, and heal the sick, heal the sick, heal the sick, heal the sick, and heal the sick with miracles. This is the only legitimate method. If there is more to it, there is not less to it, and this is at least how you start, or you are not on God’s program at all.
A program that seeks to change society by Jesus Christ would preach the gospel, heal the sick, cast out demons, prophesy, and work all kinds of signs and wonders before it even considers a direct assault on politics, education, and so on. If we are to reshape society to the point of influencing its policies, it must be an effect of expansionism by spiritual and miraculous power. No cessationist should think about a political agenda, because he does not even believe the gospel. If you face the biblical doctrine of expansionism, and then immediately think about how it applies to politics, you are already defeated. Satan has started to hijack it away from you. Satan is not afraid of politics and laws. He would be fine if you regulate human behavior without changing hearts. Christians have been in denial about how much they have deviated from the spiritual program commissioned by Jesus Christ. They have fallen so far behind that they must return focus to the increase of spiritual and miraculous power for at least several centuries before thinking about anything else, if they should ever think about anything else.