The term "Atheist Masterpiece" is meaningless. A masterpiece, whether done by a theist or atheist is just a thing, not an opinion or position,
Masterpiece
The Masterpiece was created in 2007.
the isenheim masterpiece
Masterpiece was written by Elise Broach.
The Greek word for masterpiece is αριστούργημα.
Masterpiece has three syllables.
When I Paint My Masterpiece was created in 1971.
Aristotle's Masterpiece was created in 1684.
Screaming Masterpiece was created in 2005.
Masterpiece of Bitterness was created in 2005.
Masterpiece is a noun.
An English atheist is an atheist from England.