Complex sentence: This has been predicated on a belief in the power of a practice known as strategic level spiritual warfare, though which it is believed that Christians can take control of the demonic Territorial Spirits that make cities or geographical areas both sinful and resistant to the gospel message.
Split into simpler sentences: This has been predicated on a belief in the power of a practice known as strategic level spiritual warfare. They claim that through this action Christians are able to take control of the demonic Territorial Spirits (evil spirits) that make cities or geographical areas both sinful and resistant to the gospel message.