The Christian response to Halloween is varied, and that is OK. I grew up not allowed to celebrate in any way, shape or form, however, my wife, whose dad was a pastor, went trick-or-treating. Basically, it comes down to personal conviction.
The origins of Halloween are dark and wicked, and certainly much about today's celebration is similarly evil. However, you would be hard pressed to find anyone in our modern day preparing to sacrifice in honor of the Fall harvest season. Much of the origins of Halloween are lost and irrelevant. Instead, modern celebration of Halloween is about getting dressed up and getting candy; not Satan worship.
My official position is: Halloween is what you make it. I choose to use the day to glorify God by being with my family and having fun getting candy and dressing up like farm animals. If a fellow Christian is incapable of doing such, then that is OK too. Each should do what his measure of faith permits him to do (I Cor. 8 and Romans 14).