Question: How do you know when someone is a Christmas Calvinist?
Answer: No "L"
Yes, it is the missing "L" in the acrostic TULIP.
Joking aside though, all who are particularists (who believe that only some and not all of humanity will ultimately be saved) limit the atonement in some way. The Arminian limits its power (believing Christ's "atonement" was for everybody but only hypothetically as it does not actually atone or save anyone unless man adds his faith to it) and the Calvinist limits its scope (believing that by His death and resurrection He secured a real and effectual atonement and removed the wrath of God for His people - and that the faith that saves is actually God's gift). Here's the first of a series of articles on this important issue. - JS