Yes the devil exist, very little is said about him in the Bible, accept that he was an angel who tempted Adam and Eve, rebelled against God, and is evil. Now you will hear alot of Christians, and even Catholic Christians say, that Satan’s named was Lucifer, he fell and then tempted Adam and Eve, and is still here on earth tempting us. This is all partially correct. The Church, from what I’m aware of, is that you don’t have to believe Satan’s name was Lucifer, I tend to think it was Samael sense that is what the Jews before Jesus and during Jesus taught Satan’s name was. The idea that his name was Lucifer is a misinterpretation in the book of Isaiah. Also, you don’t have to believe he fully fell before he tempted Adam and Eve. I do not, mainly because of the books like the book of Job and ancient Jewish thought on Satan. They taught he was an evil angel, but still in heaven and apart of the heavenly host, but he would accuse us day and night of sinning even though he was the one causing us to sin, and that he was trying to make us get in trouble. I think it was just before or alittle bit after Christ birth Satan fully rebelled and started the war in heaven, so his power over us could still reign because if Christ was born he could redeem us from sin. I am also a Partial Preterits so I believe Satan has no influence over the church now. Support for many of my views comes from Job 1:7 all of the context of Revelation 12, and Revelation 20, and also many other verses.