There is an adversary that seeks to kill, steal and destroy. I'll say it again, he seeks to steal, kill and destroy. Not just one or the other but all 3 of these are his purpose. He is known as Satan, Lucifer, Antichrist, Beast, Beelzebub, Accuser, Liar, Belial, Deceiver, Devil, Dragon and the list goes on. There are more names in the bible for Satan than anyone else except Jesus Christ. There is only one devil, but there are many demons. The demons are angels who sinned with Satan by following him when he revolted against God. Some are confined, but many are active in the world. They seek to thwart the purposes of God. "For our struggle is not against flesh and blood, but against the rulers, against the authorities, against the powers of this dark world and against the spiritual forces of evil in the heavenly realms." Ephesians 6:12
They even promote their own system of doctrine. "The spirit clearly says that in later times some will abandon the faith and follow deceiving spirits and things taught by demons." 1 Timothy 4:1
They can inflict diseases of men and of animals. Matthew 4:24, Mark 5:13
People who have a true relationship with Christ cannot be overcome by demons. Those who do not are fair game. One of Satan's greatest abilities is deception. He makes lies look like truth. His lies take on various forms such as cults and false doctrines. It is important to know God's word to discern the difference between truth and error. As strange as it may seem, even the demons acknowledge that there is only one God. "You believe that there is only God. You do well. Even the demons believe that and shudder." James 2:19
Now for the good news, Jesus Christ came not to condemn the world but to save the world. Do you know what that means? It means that we can be redeemed. We can have the same authority over Satan as Jesus does. "Jesus called his twelve disciples to him and gave them authority to drive out impure spirits and to heal every disease and sickness." Matthew 10:1
What a blessing. Brothers and Sisters, BE NOT DECEIVED.