A disbeliever, a denier: someone who rejects or disbelieves in God as per Islam (Arabic: الله Allāh) or the tenets of Islam; or more broadly any non-Muslim.
pantheist
noun
A person who believes in pantheism.
adj
Of or relating to pantheism.
How often have the words kafir and pantheist occurred in a corpus of books? (source: Google Ngram Viewer )