While we do know that Halloween developed out of All Hallows Eve, the night before All Saints Day, the exact details of All Saints Day's early development have been partially lost to history. We do know that the Catholic Church has often “Baptized” pagan celebrations to make them Christian Holy Days, and we know that Autumn Harvest Celebrations of different kinds have been celebrated in most every culture since the dawn of agriculture, so it is reasonable to assume that All Saints Day was placed on October 31st to take the place of those kinds of celebrations. It wasn't until recently that All Saints Day was displaced, and we developed the modern American celebration of Halloween.
Halloween is still celebrated by pagans.
Here, the connotation is that pagans have always been celebrating this “dark holiday,” and that by joining them in the celebration we are participating in their pagan religious activities.
Really, many modern pagan movements make references to ancient religions, but they can draw no real lines of continuity. This is not their holiday, it is a Christian holiday that became a secular American holiday, and the pagans are latching on to that secular holiday.
People sacrifice cats on Halloween.
While this is disturbing, it has nothing to do with my family, or any celebration of Halloween I have ever been a part of. I don't feel getting drunk and pinching people has much to do with St. Patrick either.
Teenage girls dress in sexy Halloween costumes.
Another disturbing trend, but once again, this is just one thing for parents to watch out for and avoid in their own families. Really this is a question of general modesty, not just a problem on one day.
Are there benefits to Halloween?
Yes, aside from being fun for children, I believe it gives us a good chance to familiarize ourselves with our neighbors. Also, this is the one day of the year when everyone in a neighborhood engages in sharing with each other. If only this were more of an example for the rest of the year.
Can't we just have our own unrelated Harvest Festival?
Here we go. This is the solution a lot of churches come up with. The first thing you should notice is that they are mimicking what the Catholic Church did. They are trying to de-paganize a celebration they see as pagan. The problem is that Halloween is not rooted in paganism, but in the All Saints Day remembrance of the Christians who have gone to heaven before us. By stripping this away, and making it a generic “harvest festival” they've actually taken the final step in de-Christianizing the holiday.
The real problem isn't that we dress up and share candy on Halloween. The real problem is that we forget All Saints Day. Isn't this the same thing Christians are fighting hard not to do with Christmas and Easter? Yet it was the early radical Protestant rejection of all Holy Days that led to the climate in America where Halloween would be celebrated while All Saints Day was forgotten.