But that's just Hollywood, right? Wrong! If you go back to Genesis 19, you'll see that Lot was visited by some angels (in the disguise of men). Why then would you not expect Satan and his followers to do the same; afterall, the Bible also mentions that they masquerade as servants of righteousness.
When you first became a believer, whether you knew it or not, you admitted your belief in a spiritual realm - how else then could you accept Jesus Christ for who he is. Well along with that belief comes responsibilities, and spiritual warfare is one of them. As Christians we are involved in constant, daily struggles against the world and the spritual forces of evil. The sooner you realize you're a part of this warfare, the better you will be able to stand and fight.
And how do you fight? Jesus used the scriptures to defend against temptations. As Christians we are called to follow his lead; and if you want a sure-fire way to beat Satan and his followers (whether in physical manifestation or not), you too need to know and use the scriptures.
If you don't understand what this is all about, I encourage you to pray for God to open your eyes to this area of your life. Either way, I beseech you to read and use the Bible daily so that you can more easily recognize and defend against our enemy the devil and do your best to serve the Lord Jesus Christ.