module_example.rb

module Scopes
   attr_writer :church_id
   # evaluates to
   # instance_eval do 
   #     def church_id
   #        @church_id
   #     end
   #     def church_id=(value)
   #        @church_id = value
   #     end
   # end
end

class User < ActiveRecord::Base
  include Scopes

  def find
    self.find(:first, :conditions => ["church_id = ?", church_id])
  end
end