I think people fundamentally misunderstand much of the nature of Christianity; especially when it comes to combining faith and political activism. The difference is found in the nature of behavior and separating what one does from what one is. What does it mean to "love one's enemy?"
The "Love the sinner, hate the sin" argument is valid at all times. It's easy if the sinner is neutral towards you or actively pursuing Christ. It gets dicier if the sinner is your enemy and actively pursuing your destruction. There's a difference between sinners and enemies. Self defense is not ungodly or immoral. Neither is meeting an attack with superior force of the same kind in order to defeat your enemy.
Queen Esther saved the Jews from an evilly obtained government mandated destruction by righteously obtaining a separate government mandate to meet force with force. Esther's "granted the Jews which were in every city to gather themselves together, and to stand for their life, to destroy, to slay and to cause to perish, all the power of the people and province that would assault them, both little ones and women, and to take the spoil of them for a prey."
Examples of godly men opposing their enemies are found across the Scriptures. David, Joshua and Moses all come to mind. Others opposed godless government edicts at great personal risk; the first to "speak truth to power."Remember the back story of Daniel and the lion's den? Remember the back story of Shadrach, Meshach and Abednego and the fiery furnace?
It's true that at times, God has instructed one of His children to surrender His right to self-defense as part of a greater strategy. I know of testimonies of exactly that. However, this is a specific request for sacrifice and surrender of a right from an individual, not the building of churchwide doctrine on how to deal with enemies.
Consistent biblical doctrine is that, whether they be individuals or nations, the right to defend oneself from enemies exists and is not sin. Sin enters when our motivation ceases to be love of the life God gave us and becomes hatred of the one trying to take it from us. Sin enters when we name the motivation and character of our enemy. We cannot call our enemies evil men. We can only call their actions evil. The man trying to kill me is acting evilly. But he may not be evil; he may simply be deceived.
Such is the nature of our struggle against our Islamic enemies, for example. Only God knows the heart and may accurately judge it. For us to do so is sin. But their threat is no less real for all their deception. And it may be met with godly force and destruction, even on a massive scale if that is what is needed to defend oneself. Evil or deceived in motivation is irrelevant. Trying to kill me is an evil act regardless. I may oppose it and be on the side of righteousness. This is true if the attack is an armor assault or just a blog post.
Doing so isn't seeking revenge; it is self defense! Doing so doesn't violate being at peace with all men as much as is dependent on us; we are reacting, not acting. Doing so doesn't mean we are not praying for and serving our enemies; US military hospitals routinely treat wounded Taliban. Doing so is not repaying evil with evil, it is, in fact, overcoming evil with good. Some forget such overcoming is not theoretical or hypothetical or, worse, spiritual. The overcoming is often dirty, brutal and deadly in the very real world.
The difference is found in the "Why?" and not the "What?" The difference is found in who starts a fight and who ends it. Fighting back against enemies is not just godly, it's required. The danger is in becoming what we are fighting. For Christians, that is the struggle. To destroy the works of the devil; the lies, killing and destruction - while remaining pure in heart and peacemakers. No one said it was easy; just that it needed to be done.
Be angry - sin not. Fight your enemy - don't become him. Do not repay evil for evil. Overcome evil with good. But be angry at evil behavior; fight, and; overcome. The alternative is unthinkable.