Reading the letters here on the usage of the word of 'Allah', I wish to put forward my comments.

The word 'Allah' derives from Arabic word 'Ilah'. 'Ilah' in Arabic means God. But to simply describe 'Ilah' would mean that it can refer any god ie, indefinite. As such, in Arabic it is 'Al' is added which means 'The' in Arabic.

But 'The God' is still not accurate because it could mean one or a group. Thus another 'Al' was included to make it Al-Al-Ilah, and the short form later become 'Allah'.

When the word 'Allah' is mentioned it means He is the only God. There is no god but Him. Other than Allah, all are creations. This is the fundamental of Islam. Whoever says and believe in these words, they are Muslims. Please visit this website for detail explanations of Allah.

Allah describes Himself in the Holy Quran (Surah Al-Ikhlas, 112) as:

112:1 Say: He is Allah, the One and Only

112:2 Allah, the Eternal, Absolute;

112:3 He begets not, nor is He begotten;

112:4 And there is none like unto Him.

From the above explanation, it is not right for other religions to use the word 'Allah' because it completely contradicts the meaning of the word of 'Allah'. People of other religions do not believe and worship Allah and they associate others with Allah. If other religions want to use the word 'Allah', it will deceive and confuse both Muslims and the non-Muslims alike.