What is the version of the following sentence with correct punctuation?

The term thetan was coined to eliminate any possible confusion with older invalid concepts It comes from the Greek letter theta which the Greeks used to represent thought or perhaps spirit to which an n is added to make a noun in the modern style used to create words in engineering
The term thetan was coined to eliminate any possible confusion with older, invalid concepts. It comes from the Greek letter theta which the Greeks used to represent thought or perhaps spirit, to which an n is added to make a noun in the modern style used to create words in engineering.