The spiritual value of Halloween
The cycle of holidays during the year includes three distinct categories:
Category I: Sectarian Holidays
Of course, the year is filled with totally and purely sectarian holidays like Christmas and Easter and Passover and Ramadan and last week's Diwali, which are only intended as celebrations for the believers of a certain faith. They are not universal or universalizable (OK, maybe chocolate Easter bunnies are acceptable to all). They are for the faithful holidays and they are beautiful.
Category II: Secular Holidays
The next category of holidays are those secular holidays that are for everyone but are not really spiritual. National holidays like Independence Day and New Year's Day and, yes, Super Bowl Sunday are examples of secular holidays. They provide unity for a national culture and they do not require sectarian beliefs. Some want to include Christmas as a national secular holiday, but I am not buying it. Christmas is a holiday celebrating (for Christians) the birth of Christ. Santa is an imposter.
Category III: On the Fence Holidays
Finally, there are those holidays that might once have had religious origins, but over time they have been secularized and are now acceptable for people of all or no faiths. The best of this bunch is Thanksgiving. It probably began its life in the 17th century as a Pilgrim celebration of the Jewish holiday of Tabernacles (Sukkot), but it has become a national celebration of thankfulness (and turkey and football) that brings all families together for a meal with almost the identical menu throughout the country. Other once-religious-but-now-secular holidays are Valentine's Day (not really St. Valentine's Day any longer) and Halloween.
Halloween definitely mixed religious and pagan elements in its beginnings. It may well have originated as a pagan Celtic harvest festival called Samhain. In the Christian calendar Halloween is the evening before All Hallows Day, which is a holiday celebrating saints and deceased righteous ones. However, the religious elements of Halloween have by now been washed clean in a shower of chocolate peanut butter cups.
Though I do not agree with it, here is the best case against Halloween:
Sugar. It is a vile addictive substance that causes obesity and tooth decay. The sugar jag caused by Halloween has sustained generations of dentists.