The Bible defines sin as transgression of Gods law. Demons are fallen angels who are trapped here on earth after being cast out of heaven. They work to do several things. First is to obfuscate the truth of the Bible and the path to salvation. Second is to tempt and deceive human beings into surrendering themselves to their own selfish desires so they sin and are then condemned. The ultimate goal is to prove that God is unreasonable and His laws aren’t just and can’t be kept. By proving this, they hope to escape their own judgement and have their own separate kingdom. On the other side of things, The Father in heaven has enacted the plan of salvation through His son Jesus in order to prove that the law can indeed be kept and that it is a law of love and liberty. All this while also saving the humans who have been caught up in the conflict in order to demonstrate His love, patience, and mercy.