The devil is a very familiar creature to most Christians. The devil (or Satan, Lucifer) is a fallen angel (a demon) who leads an unknown number of fellow fallen angels who oppose God. The common Christian belief and teaching, is that Lucifer was once an angel who let his pride get the best of him. Lucifer (with his pride as the driving force behind his decisions) managed to get 1/3rd of the Heavenly Host to rebel against God. Lucifer led his army in a cosmic battle against God who in turn sent out an army led by St. Michael the Archangel. Lucifer and his followers were ultimately defeated and cast down to the earth. Jesus Christ actually refers to the falling of Lucifer to the earth in Luke 10:18, “And He said to them, “I was watching Satan fall from heaven like lightning.”
Lucifer, along with those other fallen angels, became twisted and perverted by their fall. They retained though many of their angelic powers but found that God had placed limits on what they could and could not do. Even in their fallen state, the demons are subject to God’s will like any other part of creation. They roam the earth seeking people to victimize as St. Peter points out in 1 Peter 5:8, “Be of sober spirit, be on the alert. Your adversary, the devil, prowls around like a roaring lion, seeking someone to devour.” Christians are taught that the best way to combat against the Devil and demonic forces is through our faith. Most Christians refer to Ephesians 6:10-17 as the way in which one can defend and move against demonic forces.
Last of all I want to remind you that your strength must come from the Lord’s mighty power within you. Put on all of God’s armor so that you will be able to stand safe against all strategies and tricks of Satan. For we are not fighting against people made of flesh and blood, but against persons without bodies—the evil rulers of the unseen world, those mighty satanic beings and great evil princes of darkness who rule this world; and against huge numbers of wicked spirits in the spirit world.
So use every piece of God’s armor to resist the enemy whenever he attacks, and when it is all over, you will still be standing up.
But to do this, you will need the strong belt of truth and the breastplate of God’s approval. Wear shoes that are able to speed you on as you preach the Good News of peace with God. In every battle you will need faith as your shield to stop the fiery arrows aimed at you by Satan. And you will need the helmet of salvation and the sword of the Spirit—which is the Word of God.
Christians believe that through our faith in God we can not only defend ourselves from demons but we can also fight back against them. Many Christian denominations feature offices or people who are trained in that denomination to handle demonic cases. In Catholicism for example, Exorcists are Priests who have undergone specialized training that equips them for ministry work that involves possessions and demonic issues. Different denominations have different ways of approaching spiritual warfare though so not all agree on who can and cannot participate in certain areas of spiritual warfare.
In Christianity prayers to the Lord are used to drive away demonic forces and commands in the name of the Lord are also used. It is stressed however that faith in the Lord is the ultimate key to defending from and driving away demonic forces. Through Jesus Christ, Christians believe that we have the authority to rebuke demons. Lack of faith in Jesus Christ means that one has a lack of authority in rebuking demonic entities as pointed out in Acts 19:13-16, “Some Jews who went around driving out evil spirits tried to invoke the name of the Lord Jesus over those who were demon-possessed. They would say, “In the name of the Jesus whom Paul preaches, I command you to come out.” Seven sons of Sceva, a Jewish chief priest, were doing this. One day the evil spirit answered them, “Jesus I know, and Paul I know about, but who are you?” Then the man who had the evil spirit jumped on them and overpowered them all. He gave them such a beating that they ran out of the house naked and bleeding.”
Demons in the Christian religion are seen as fallen angels who possess a lot of supernatural power. They, like humanity, have free will and at one time decided to rebel against God. Demons, unlike humanity, do not have the ability to repent of their sins and thus are stuck with the decisions that they made. This is one reason for their hatred against humanity. They also hate humanity because we are made in God’s image and thus we reflect God which is a constant reminder of what they lost. They also hate humanity because of humanity’s relationship to God and God’s ultimate love for humanity. This inspires jealousy in them and they also believe that by destroying humans one by one, they can get even with God.