"But if I drive out demons by the finger of God, then the kingdom of God has come upon you. 21When a strong man, fully armed, guards his house, his possessions are secure. 22But when someone stronger attacks and overpowers him, he takes away the armor on which the man relied, and then he divides up his plunder.…"
It is important to keep everything in context. Jesus is here describing the demons as the "strong man" and it is He, Jesus, who comes along and despoils him and drives him out by the power of God and not with a carnal weapon. This is talking about salvation and not self-defense.
It has been ingrained in us from our earliest childhood to be a good patriot, and being a good patriot is not a bad thing as long as we know to whom our loyalty is due. With our rebirth came a new loyalty, to a new Kingdom and a new King; now we must decide to which kingdom we will show our loyalty; we cannot serve two kings. If our loyalty is to this world and its kingdom then, by all means, serve its king in every way possible: militarily, politically, and socially. If our loyalty is to the Kingdom of Heaven and its constitution then serve it alone, and to your greatest ability. As Christians, we are now serving our King in another world with a specific mission to perform. As a soldier of the Cross we must not allow ourselves to get involved in civilian affairs and so by be distracted. Fighting the battles of this world and its leader Satan we are distracted. Yes, stand up for the poor and the weak, but do no harm.
The governments of this world were instituted by God to maintain a modicum of peace till He returns. Those governments were not for, or about, those who are citizens of another country. Yes, we obey the laws of the country we now occupy, but only to the extent that we do not disobey the Kingdom laws of which we are now citizens. The Bible teaches us that as we draw nearer to the end that we should not be surprised to see the populations of the world become ungovernable and perverse just like Sodom. We do not hear of Lot or Noah being involved in government, but rather they were concerned about hearing the Lord and obeying His commands. If they would have gotten caught up in the affairs of their respective domains the world would be a different place today; remember Lot's wife, her heart was in Sodom with its issues: their home, their friends, their country.
Any kind of defense is unbelief and has no part in the Kingdom of God. Jesus told us that the Kingdom of God had come unto us. Along with that Kingdom came the whole responsibility of Kingdom citizenship and obedience. For example, if we go to another country as an American citizen we must obey that country's laws, as long as those laws do not require us to become disloyal to our own country. If we disobey our home country laws then we can be prosecuted by our home country. If we are living in a country whose people and laws are despicable then, to remain loyal to our home country, we may be forced to disobey that countries laws and even give up our lives. In the Kingdom of Heaven there will be no violence either of self-defense or national defense, everyone will be non-resistant to evil (there will be no evil in Heaven) as Jesus commands us to be here in this foreign country Matthew 5:39. If our heart is with this world then we should obey it, if our heart is in Heaven then obey it.
The question of defending my family if attacked is the question that always comes up when this Kingdom lifestyle is presented. Would I protect my family? The answer is yes, of course. I have put in place a plan of protection that is the absolute best plan, I have introduced each member of my family to the Lord and He has promised to protect them if I will stay loyal. What more can I do? I own no weapons of self-defense and do not have great strength, I am at the mercy of God to fulfill His promise. If I, or a member of my family, is harmed then I will still trust the Lord. I will of course reason with the attacker and try and stop the attack, that is all I can do. Think about this example. I do not bow to idols, call them flags or anything else, and a government official demands that everyone must stand when a certain article is produced or their whole family would be killed. I would not do it. Or, let's say a terrorist demands that you detonate a dirty bomb in a highly populated area and kill maybe a thousand people, would you do it to save the lives of your family? The answer to both of these questions are the same, I must stay loyal and obedient to my Lord.
Every Kingdom Christian has a constitution to which he is obliged to obey under every circumstance, there is no plan "B".