Mark all of the text to not check spelling or grammar. You can do this by Ctrl+A and then under the Review tab under Language > Proofing language, make sure the box to not check spelling or grammar is checked.


You can also do this with a character style for individual words or passages. Such a style is described toward the end of this Article:
Proofing Language Keeps Changing - Solutions - How can I keep my proofing language from changing?