Exodus 20:13 (NKJV)
13 “You shall not murder.
Exodus 22:1–3 (NKJV)
22 “If a man steals an ox or a sheep, and slaughters it or sells it, he shall restore five oxen for an ox and four sheep for a sheep. 2 If the thief is found breaking in, and he is struck so that he dies, there shall be no guilt for his bloodshed. 3 If the sun has risen on him, there shall be guilt for his bloodshed. He should make full restitution; if he has nothing, then he shall be sold for his theft.
In one of his more unguarded moments, then Senator Obama (April 2008) commented on how people frustrated with government's inability to deal with issues will often "get bitter" and when they do "they cling to guns, or to religion, or to antipathy...." He backtracked a bit when his opponent (Sen. Hilary Clinton) took him to task but the remark probably reflects his continuing assessment of those who oppose additional government restrictions and regulations on the private ownership of firearms.
The Senator's (then) remarks are accurate in a broad sense though. Many Americans, including Evangelical Christians, do hold some idea that private ownership of firearms is a God-given right. As such, taken literally, this means that the ownership of weapons would transcend the constitution. If the right to keep and bear arms is a God-given right then it would not matter, ultimately, whether the constitution authorized it or not.
The question is worth exploring.
I am restricting my thoughts here to private ownership of weapons for reasons other than recreation or hunting. Hunting today is not really necessary to survival as it often was in 1791 though some die-hards would probably say that mental health would be endangered if they had to give it up. The core issues in the current debate is ownership for the purposes of "self-protection" (life & property) and, at the extreme, as a check and balance against government tyranny. Thus the question is "does the economy of God authorize or, in fact, require that His covenant people be adequately equipped for self-defense or for service in an ad hoc militia if necessary?"
There are a range of opinions on this and various theologians come down to different conclusions. Most will say that the question is highly nuanced and therefore there is a certain degree of ambiguity in it. Martin Luther went so far as to say that true Christians should always turn the other cheek. He then went on to add that very few people, even in the Church, are true Christians. Therefore, he said that God desires evil to be curbed or hedged in so therefore all those "other" people, especially when they are the magistrate, should be armed. This is necessary to keep evil people from multiplying because, in his famous phrase, "frogs need storks." (Storks eat frogs and hence keep them from over populating the pond.) Luther thus planted his feet firmly on both sides. His later support of the armed suppression of the Peasant Rebellion has clouded his reputation to some degree.
Calvin also straddled the fence to some extent.
I think that there is a clear teaching that "vengeance" (especially murder in pursuit of vengeance) is absolutely disallowed to the Christian. Further, I think that it is clear that our Christian duty is to "love" them. Those two guiding principles give a general framework in which to find some balance.
I don't believe we have to go as far as R. Rushdoony and discover that God's command to defend the helpless against violent injustice confirms every man into a "private police" force. Certainly the negative command to "not murder" has the positive corollary that we must take every opportunity to defend life against unjust violence. Does this mean that God has not only given us the right to have weapons but mandates that we do? I don't think so. Not every defense of life requires that a life be taken in prevention. I do believe though that it is our God given duty to protect the lives of those under our care even if we have personal discretion over whether or not to exercise self-defense for our own persons. I think it entirely within the bounds of our Christian freedom to own guns for self protection if we so desire.
Given that our religion allows us to own guns but does not require it of us, is it our Christian duty to submit to a government law that prohibits private ownership of weapons? This is more tricky.
Jesus' words do not completely resolve this situation. In Luke 22 Jesus positively commends the ownership of swords and when asked by his disciples if they should resist the ones sent to arrest Him, he says "permit even this." This cannot be taken any other way than Jesus saying, "In this situation, allow me to be arrested without violence." Jesus does not condemn the disciples for asking the question and therefore seems to affirm the literal possession of weapons. In the other Gospel accounts Jesus' actions fit into this framework. Jesus' statement before Pilate that His Kingdom is not of "this world else my servants would fight" has to do more with the nature of His government and rule than the absolute proscription for weapon ownership.
That still does not give us absolute clarity with respect to any governmental sanctions against it.
Thus, I have to conclude that the Scripture does not say that we have an absolute right to ownership of firearms and that Christians cannot appeal to Scriptures in that regard. If a man is called upon to defend his home and is without firearms that doesn't mean that he cannot find other means of doing so. It might require us to carefully consider how to equip our homes and possessions so as to minimize the necessity for firearms at all.
But, do I believe that it is morally wrong for the government to so restrict the citizens? Yes, I do. But God, in His providence has established government over us and has given us instructions that we are to obey that government. There are limits to this and civil disobedience is a Christian option with 3000 years of history to back it up. It is foolish to believe that private ownership of weapons in today's society will ever, effectively, provide for a militia that could take on the Federal government in open warfare. The idea of a private militia itself is also questionable. To be part of a militia, a Christian would have to swear to take orders and work under that militia's authority. That is not the same thing as giving allegiance to a new government. Government is far more comprehensive than simply its armed forces. The Colonials did it right. They had a separate government in place when they declared their independence and therefore Christians could, in fact, give their secular allegiance to that cause.
So, I believe that Christians should resist the government's immoral and unconstitutional attempts to restrict private ownership of weapons but I do not believe they can argue that it is a God-given right for them to own them. If the country divides and a separate movement is founded with the intention of over turning the government in some kind of coup, then Christians should be very careful in how they react to that. At that point it is no longer a question of owning firearms, it is a question of submitting to God first and foremost.