It’s actually a merger of two holidays. The Pagan Celtic holiday “Samhain” and the Catholic “All Souls Day.” Samhain was the harvest festival which ushered in the “dark half” of the year. See Mishna Avoda Zara regarding the holiday of Saturnalia which was not dissimilar. X-Mas is based on it. All Souls Day is the Catholic prayer holiday for all the souls who didn’t make it into “heaven” or are lingering in purgatory. Either way it’s about death and darkness.
There is no doubt that this “holiday” is rife with tumah and idol worship. It is antithetical to Judaism. My own minhag… NO candy to be mesamayach the Goyim or nonreligious Jews on that day. Then again I don’t give gifts on Hannukah either because I feel it is mimicking a minhag of Avodah Zara.