History probably gives us some insight. Halloween is rooted in religion, but those origins are a convoluted mixture of Christian observances and pagan rituals.
The LGBTQ community’s relationship with religion has historically been, and continues to be, tenuous; maybe we recognize ourselves to that aspect of the October 31 celebration. Halloween is generally considered a decadent holiday so much so that Christian bloggers suggest alternatives like, we kid you not, a Reformation Day Party. (One such blogger inexplicably suggests a Noah’s Ark Party as an alternative to trick-or-treating. Now that just screams: “I need gay friends!”)