If a demon drives/entices me to commit adultery, is it now somehow not adultery? Or am I somehow exempt from guilt? Or, if a demon tempts me to steal something and I steal it, am I exempt from guilt? Of course not! demons can have limited influence and can tempt a believer, but can't "make" us do anything. That's like the child eating the cookie they were already told no about by dad, and saying "the devil made me do it." There is personal accountability. You opened a door to the demonic influence, or at the very least, when demonic oppression/attack came, you didn't shut the door in it's face by the Word of God, prayer, and the Spirit of God. Is a True Believer powerless against demons? OF COURSE NOT! We have power in Christ to cast them out of unbelievers and to tell Satan to get behind us.
"When we are tempted....He will not allow us to be tempted beyond what we can bear.......but .He is faithful to provide a way of escape..."
"Each man is enticed and dragged away by his own lusts"
As far as David killing people, Samson killing people, Samuel killing, etc. Again, there seems to be a great lack understanding of the differences in the Old Covenenant & the new. David also had more than one wife. Who's making excuses for that today? They also made animal sacrifices. Anyone saying that's OK today?
These things were OT types and shadows of greater "war", greater "murder", and greater "enemies" to come. Now, in the New Covenant, "our enemies are spiritual wickedness in high places", and "the weapons of our warfare are not carnal, but mighty in God for the pulling down of strongholds". And the only murder recorded in the New Testament ordained by God is the killing of sin, the "putting to death the deeds of the flesh", and the "mortifying of the flesh".
Now, we are not to presume the role of taking anyone's life, but are to "entrust ourselves to Him", to "leave Room for God's wrath, for vengeance is His and He will repay". If the Lord needs to strike down someone (like Annanias & Saphira, those taking the Lord's Supper in an unworthy manner, etc.), He will do it Himself, and doesn't need the fleshly intervention of His children. H can use the bloodthirsty heathen to carry it out if He decides.
There is NOT ONE example of a New covenant "murder" or taking ones life into ones own hands by violence. Not one. In fact, when Peter drew the sword (being stuck in his mindset also in the Old Covenant), Jesus rebuked him sharply, told him to put his sword away, and said that he who lives by the sword shall die by it. Jesus entrusted His life to the Father &submitted to the cross, and LAID DOWN HIS LIFE. The apostles got filled with the Holy Spirit and all did the same. The early church did the same. Believers down through the ages have all done the same.
I have studied the Masada mass suicide a bit, and it is esteemed as some great noble thing by many as a source of pride. It was a mass suicide. Period. I'm not judging them, but they obviously hadn't entrusted their lives fully to God, or they wouldn't have taken their own lives. Some people had to kill their own babies and children there. WHAT'S NOBLE ABOUT THAT? And where is the trust in the Lord's care in that? I know the story and I know what was bearing down on them, somI don't judge them harshly, but it is what it is: a mass suicide.