1. What is Allah
The word “Allah” is simply the Arabic word for “God” – and there is should only be One God. Let there be no doubt – Muslims worship the God of Noah, Abraham, Moses, David and Jesus – peace be upon them all. However, it is certainly true that Jews, Christians and Muslims all have different concepts of Almighty God. For example, Muslims – like Jews – reject the Christian beliefs of the Trinity and the Divine Incarnation. This, however, does not mean that each of these three religions worships a different God – because, as we have already said, there is only One True God. Judaism, Christianity and Islam all claim to be “Abrahamic Faiths”, and all of them are also classified as “monotheistic.” However, Islam teaches that other religions have, in one way or another, distorted and nullified a pure and proper belief in Almighty God by neglecting His true teachings and mixing them with man-made ideas.
First of all, it is important to note that “Allah” is the same word that Arabic-speaking Christians and Jews use for God. If you pick up an Arabic Bible, you will see the word “Allah” being used where “God” is used in English. This is because “Allah” is a word in the Arabic language equivalent to the English word “God” with a capital “G”. Additionally, the word “Allah” cannot be made plural, a fact which goes hand-in-hand with the Islamic concept of God.
It is interesting to note that the Aramaic word “El”, which is the word for God in the language that Jesus spoke, is certainly more similar in sound to the word “Allah” than the English word “God.” This also holds true for the various Hebrew words for God, which are “El” and “Elah”, and the plural or glorified form “Elohim.” The reason for these similarities is that Aramaic, Hebrew and Arabic are all Semitic languages with common origins. It should also be noted that in translating the Bible into English, the Hebrew word “El” is translated variously as “God”, “god” and “angel”! This imprecise language allows different translators, based on their preconceived notions, to translate the word to fit their own views. The Arabic word “Allah” presents no such difficulty or ambiguity, since it is only used for Almighty God alone. Additionally, in English, the only difference between “god”, meaning a false god, and “God”, meaning the One True God, is the capital “G”. Due to the above mentioned facts, a more accurate translation of the word “Allah” into English might be “The One -and-Only God” or “The One True God.”
2. Who is Allah
Allah Said in the Quran that He is Allah, the most self sufficient Master, that there are none comparable to Him:
“Say (O Muhammad) that He is Allah the One. Allah, the self sufficient Master. He begets not nor was He begotten. None that comparable to Him” (al-Ikhlas 112:1-4)
More importantly, it should also be noted that the Arabic word “Allah” contains a deep religious message due to its root meaning and origin. This is because it stems from the Arabic verb ta’allaha (or alaha), which means “to be worshipped.” Thus in Arabic, the word “Allah” means “The One who deserves all worship.” This, in a nutshell, is the Pure Monotheistic message of Islam.
There are some people out there, who are obviously not on the side of truth, that want to get people to believe that “Allah” is just some Arabian “god” which is the Moon god, that according to Robert Morey it is found as the archeological artifact, and that Islam is completely “other” – meaning that it has no common roots with the other Abrahamic religions (i.e. Christianity and Judaism). First of all, to say that Muslims worship a different “God” because they say “Allah” is just as illogical as saying that French people worship another God because they use the word “Dieu”, that Spanish-speaking people worship a different God because they say “Dios” or that the Hebrews worshipped a different God because they sometimes call Him “Yahweh”
The second, the most powerful denial of this weak claim is the Qur’an itself as stated in Fussilat 41:36
And if (at any time) an incitement to discord is made to thee by the Evil One seek refuge in Allah. He is the One Who hears and knows all things.
Fussilat 41:37 Among His Signs are the Night and the Day and the sun and moon. ADORE NOT THE SUN AND THE MOON BUT ADORE ALLAH WHO CREATED THEM if it is Him ye wish to serve
In the Qur’an, Allah describes the sun and the moon as submitting to Allah’s Law. That is, the sun and the moon follow courses exactly computed, according to the Law of Allah. It is stated clearly in the Quran: Luqman 31:29
Seest thou not that Allah merges Night into Day and He merges Day into Night; that HE HAS SUBJECTED THE SUN AND THE MOON TO HIS LAW each running its course for a term appointed: and that Allah is well acquainted with all that ye do?
It should be clear that Allah is not goddes of the moon, since He declare that it is merely His creature that obey to His law. Allah is the only one God, although he has other Greatest Names, called Asma’al Husna, as said in Holly Quran:
20:8 “Allah, There is no god but He; His are the Greatest Names.”
7:180 “Say: Call upon Allah or call upon the Beneficent God (al-Rahman); whichever you call upon, He has the Greatest Names.” (Qura’n, 17:110) To Allah belong the Greatest Names; therefore, call on Him thereby, and leave alone those who violate the sanctity of His Names…”
3. Is Allah, the God of Muslim, the same with the God of other religions?
The most important point here is that Christians who speak Arabic refer to God as Allah and Rabb (Lord) just as Muslims do. So, for a Christian web site to say that Muslims worship Allah, the ancient moongod is preposterous. They might as well tell their Christian brothers and sisters who speak Arabic that they are worshipping the moon god too since the word “God” that appears in the Bible, it is in Genesis 1:1, when it states:
B’reshit bara ELOHIM et ha-shama’im, V’et ha-arets. In the beginning, God created the heavens and the earth.
While Christians will forever speculate on the word “Elohim” , honest Hebrew speakers would admit that this archaic word for God has a history that is lost to us. The “royal plurality” hypothesis may be a possible explanation for why the word is plural, but this seems to have been unknown to early Hebrew speakers (such as the Jewish missionary who, according to the Kuzari, competed with Muslims and Christians to convert the king of the Khazars in the eighth century). It is difficult however to translate this word to “gods,” as the Hebrew text conjugates the verb “to create” in the singular.
Regardless, Elohim is a plural forum of a more basic root-word for God, (eloh) The root itself finds its origin with an older root, el, which means God, deity, power, strength, et cetera. So one of the basic Hebrew words for God, (eloh), can easily be pronounced alah without the diacritical marks. Not surprisingly, the Aramaic word for God is (alah). This word, is spelled alap-lamad-heh (ALH), which are the exact corresponding letters to the Hebrew eloh. The Aramaic is closely related to the more ancient root word for God, eel.
The Arabic word for God, Allâh , is spelled in a very similar way, and is remotely related to the more generic word for deity, (ilah). We are quickly starting to notice the obvious linguistic and etymological connections between the respective words for God in these closely related Semitic languages (e.g. Allâh, Alah, and Eloh being related to Ilah, Eel, and El, respectively). Allah is the same with Eloh, El,Alah, eel. To proof this is very simple. Remember that when Jesus peace be upon him was put on the cross, he cried to GOD Almighty and said “Eloi”, which is derived from “Elaw” or “Allah”. He didn’t say “Yahwahoi”!
Many stubbornly Christian still insist that their God name is Yahweh or Jehova, as refer to Exodus 3:15 ” God spoke to Moses, saying: ‘Thus shall you speak to the Israelites: The LORD [Hebrew: YHWH], the God of your fathers, the God of Abraham, the God of Isaac, and the God of Jacob, has sent me to you: This shall be My name forever, this My appellation for all eternity.’ (Exodus 3:15; Psalm 135:13)”
To answer this, the word “YHWH” or “Yahweh” or “Jehovah” is indeed not His ORIGINAL name, but the appellation (title) for the Almighty GOD. This is perfectly fine, because Jews, Christians and Muslims call on to GOD Almighty as “The LORD” or “The GOD”, which means “Yahweh” or “Jehovah” in Hebrew and “Al-Rab” in Arabic. “Al-Rab” in Arabic and “Yahweh” in Hebrew and the other translations in all other languages are indeed GOD Almighty’s title. But they are NOT His original Name! Notice that Yahweh (the Lord which is the same as Rabb, in arabic) is only nick name or title for the God. It Allah, His name, or Eloy such as Jesus cried when crossed, is His name according to Quran and Bible, spelling on different language only. Those who want to read further discussion on this things should refer to here.
 Such as the claim propagated by Robert Morey in his work, The Moon-god Allaah in the Archeology of the Middle East. For a discussion of this work, please see the following links: (http://www.islamic-awareness.org/Quran/Sources/Allah/moongod.html)