Black Butler question?

It is satanic...Sebastian is a Demon its the physical representation of Ciels Faustian contract with Sebastian. As it appears in Ciels eye, it is an Inverted Pentagram which is believed to be evil where as a non inverted Pentagram is a symbol of protection. I'm assuming your parents aren't familiar with that though so just tell them its a Pentagram which is a sign for protection, that should appease anyone who asks.

Well, an inverted pentagram (the symbol on Ciel's eye) is considered the sign of the devil. However, if your parents saw/read Kuroshitsuji, they'd probably see that while it's about demons and soul and all that, it's not really "satanic". But yes, the inverted pentagram is satanic.

It resembles the bond or connection ciel has with Sebastian, like there spirits are connected forever until death. Not exactly satanic