Back masking could mean a series of things, but when it comes to music it could very well be a coincidence. Because if someone listens to a song backwards it makes no sense and sounds scratchy. So if you ask a random person they will say they hear a bunch of scratches. But if you ask a religious person they will say its the devil. However there are some musicians who actually do have hidden messages in the reversed version of the song. But in my opinion, it just seems all like a big coincidence.
       Most people when asked about back masking, or reversed songs will think of "stairway to heaven" by Led Zeppelin. But there are more songs out there, such as "Reverse Will" from the video game "Silent Hill". The original song gives off an eerie sound as if something bad is about to happen, which makes it kind of scary. However, after listening to it reversed you can slightly hear the prayer "Now I lay me down to sleep" / "I pray the Lord my soul to keep" / "If I should die before I wake" / "I pray the Lord my soul to take". Now this may be intentional because the reversed song is played in "Silent Hill 2" and being the nature of the game, it would make sense that the back masking of this song would be a prayer of some kind.
       People over look the songs and just go on what they hear from the normal version and what that story has to say. But then there's are songs that tell a much different or refer to the actual song once said backwards. Such as Tools "Intension" which sounds like any other Tool song, it can either be good, messed up and/or tell a story. But for this song, once listened to backwards you can hear "Listen to your mother. Your father is right. Work hard. Stay in school. Listen to your mother. Your father is right. Listen to your mother. Your father is right." This can be heard at the beginning of the song, which is strange because the song already sounds like its in reverse, or maybe it is and this is the normal version? Either way, the original version sounds creepy until the singer begins to sing, which still gives off a creepy-ish vibe. But when reversed it can sound a bit creepy and the new lyrics may be hard to hear, but they are in there.
       So what does this mean? Do all songs have secret demonic meanings behind all of them? No, not all, or none of them could be for all we know. Because the new lyrics are found from what people think they are hearing versus whats actually being said. That's what people need to understand, and if it sounds like someones talking about Satan, that doesn't mean they actually are. So just enjoy the song for what it is instead of being caught up in the reversed messages, if there are any.