The Bible seems to say or maybe it does say we either have God’s spirit or we have evil spirits, but evil spirits don’t necessarily translate into terrible evil, it only does if the right conditions exist. For instance, some of the Pharisees apparently had so much wickedness that Jesus called them “Children of the Devil”. Well, that would be fitting considering a few of them had Jesus crucified, right?
And let’s look into more Biblical reasoning. Well, Jesus mentioned that an empty house, which would be someone who was spirit filled and then chose to stop being that way (no prayer etc.), would possibly or maybe surely get filled with even more wicked spirits than before the person was even living for God!
I mean, think about it. The lesson here is sort of unclear but clear in its advice that people must keep their lamps burning. It’s simply a war situation and this was also made known when Jesus stated Satan’s goal is to steal, kill, and destroy.