Interestingly, like Christmas was, the religious aspects of Halloween were specifically de-emphasized by the dominant religious orders of the time, leading to (re?)seculrization of the holiday. The protestants weren't a big fan of venerating saints, or some of the underlying ideas of the the group of holidays (like the idea of souls resting in purgatory until those days) as those ideas were based in some of the philosophical differences they had with Catholics.

Good luck taking a feast and dress up day from the people though once you remove the religion out of a holiday.