I believe the whole Bible, not just the New Testament. I also believe that the Old Testament applies to us - whether directly or by principle - unless the NT specifically states that portion of it is done away with or fulfilled, etc. Therefore I still believe we are to defend our families, our homes, and our nations.

I see from Scripture that as a Christian I am not to take personal vengeance against my enemies - but I do not see where I am not to fight my countries enemies (and there is no such thing as a Christian nation, so we can't assume that God doesn't want our nation to go to war because we are a "Christian nation").

What about the passage where John the Baptist was speaking to the soldiers? He did not tell them to stop being soldiers or never fight.

Luke 3:12-14 Then came also publicans to be baptized, and said unto him, Master, what shall we do? And he said unto them, Exact no more than that which is appointed you. And the soldiers likewise demanded of him, saying, And what shall we do? And he said unto them, Do violence to no man, neither accuse any falsely; and be content with your wages.

In this context, I believe the reference to not doing violence is to not extorting others, not controlling others by force.