Mulhid

Mulhid (Arabic: ملحد mulhid, plural ملاحدۃ malaahidah) is a person who rejects the existence of God (Arabic: الله Allāh) and disbelieves in the Last Day, also known as an Atheist. A Mulhid is considered a Kafir because of that person's Kufr (Disbelief).

The Qur'an refers to Atheists in this verse:

And they say, "There is not but our worldly life; we die and live, and nothing destroys us except time." And they have of that no knowledge; they are only assuming. [Al-Jāthiyah 45:24]