Because I believe a good portion of what Jesus did on the cross and when he resurrected is the defeat of evil powers, the fact that we don't recognise them and where they still exist and cause harm to people seems wrong... My church is involved with some pastors in Africa. The testimonies out of there are incredible, in part because the evil side still manifests so clearly and everyone knows about demonic oppression and it's effects they also know the effects that Jesus smashing those powers has on their lives.