Deciding whether a symbol is used for the devil, another god, or not depends on the person's belief and intent. If you decide to use it for your own meaning then do it. It's all about what you believe in. Not everyone believes in the devil though and does not believe a pentagram or pentacle is evil. I believe it's good nor bad, but it's just are minds that give it those characterics for what someone is using it for. If I am correct; to correct witchessong, not everyone who works with demons believe in the devil either so it's not unless which she stated. To me, a pentagram/pentacle can have a infinite amount of definitions. The reason why is because a belief does not make it true and a pentagram/pentacle is used for so many things and is in several paths as well. Also Christianity may have beliefs about a devil, but it is not the only place he or she has been stated in. You have other people outside of the religion who works with him and other's that interpret him or her differently. Like said above, a pentagram is just a star and a pentacle is a circle with a star in it. Also magick can or cannot come from the devil. Again, it is based on how you believe in it.
If you don't feel comfortable using a pentagram then feel free to switch it with another symbol you want to use. No harm in that at all.
Hopefully this helped clear it up.