Question: Is it permissible to say “God” instead of Allah? Are there equivalents for the word “Allah” in other languages?
ANSWER
Allahu ta’âlâ’s Names are tawqîfî; that is, it is permissible to use His Names shown by Islam and not permissible to use other names. For instance, Allahu ta’âlâ may be called “Âlim” (the Omniscient), but it is not permissible to use “faqîh” which also means “Âlim,” for Islam does not use “faqîh” for Allahu ta’âlâ. There is no religious obstacle to using the word “god” in the meaning of “ilâh.” For example, it is permissible to say, “Ox is the god of Hindus” or “Allah is one; there is no god but He” or “Our god is Allah.” But it is not permissible to say, “Our Allah is God.” You should understand this fine point well.

(Ilâh: God. God means ma’bûd [that which, or who, is, or is to be worshipped]. Anything which is worshipped is called a god. The Name of Allahu ta’âlâ is Allah, not God. There is no ilâh [god] besides Allah.)

Allahu ta’âlâ’a Names are infinite. It is well-known that He has one thousand and one Names; that is, He revealed one thousand and one of His Names to human beings. In Islam, ninety-nine of them, called Asmâ-ul Husnâ, were revealed.

It is not permissible to say “God” instead of the Name “Allah” or “Allah” instead of the name “God,” because god means ilâh, idol. As Assyrians accustomed the Turks to worshipping the sun and stars, they would worship the sun when it dawned. For this reason, the sun’s name became tanyeri and finally tanrı (god).

The word Allah is a proper name. There is no equivalent for it in any languages. This word does not have masculine or feminine form. However, the word “god” has equivalents in every language and also masculine and feminine forms in some of them, e.g., ma’bud and ma’buda (in Arabic), tanrı and tanrıça (in Turkish), God and Goddess (in English), Dieu and Deesse (in French), and Gott and Göttin (in German). None of these words can be used instead of the name Allah. It is necessary to use only the word Allah when you refer to Allah, because Allahu ta’âlâ declares, “My name is Allah. Worship Me by saying Allah.” We must use the word He has commanded us to use. When the word ilâh is meant, all nations can use its equivalents in their own languages, but the word Allah is the same in all languages. (Endless Bliss)

It is purported in the Qur’ân al-karîm:
(Allah is only one god.) [Sûrat-ul-Nisâ’, 171]

(I am Allah. There is no god but I.) [Sûrat-u Tâhâ, 14]

(Your Mawlâ is Allah.) [Sûrat-u Âl-i ‘Imrân, 150]