Prof. Sean Lucas of Covenant Seminary has posted a blog critical of churches that use the church year calendar. You should read the comments attached. They are pretty devastating to his argument from the "regulative principle of worship" and the notion that using such a calendar "binds consciences."
Also, check out John Allen Bankson's nice, succinct argument against this kind of reasoning at his blog Know Tea.
I've commented on this myself in my posts on Christmas. The relevant posts are
A Parking Lot parable
Is the church year an imposition on the conscience of Christians?
Don't these annual festivals smack of OT religion?
Is there any warrant in the Bible for a church year?
Of what use is the church year?