Is 'Allah' the same god of the Jews and Christians?
Yes. The word in Hebrew came from "El" and in Arabic from "Elh". The
word for "god" (note the small 'g' in English) is "Elah". Compare this
to "Eloi" and "Eli" in the New Testament.
The word "Allah" is the perfect word to describe the God of Jews and
Christians as it does not permit gender nor plural. Therefore, when the
word is used as in "Eloihim" or "Allahumma" (these would appear at first
to be plural and/or female genders) it becomes clear it is the royal
usage such as a king would use in referring to his royal station while
make a decree of some type. The king would state, "We decree the
following..." and he is actually talking about his royal position rather
than plural status.
There is no word in English for the "God" of Israel, the "God" of
Jesus. This explains why the spelling remains the same whether speaking
of a false "god" or pagan idol and the "God" of Abraham or Moses or
Jesus (peace be upon them). Note the use of the capital "g" (G). This is
the only way English can present a difference between the two. In the
Semitic languages it is easy to distinguish the difference between a
"god" and "The God" due to the structure of the word itself.
Evidence for this is quite simple. Visit any motel or hotel and remove
the Bible located in the drawer next to the bed (placed they courtesy of
the Gideon Society). Note inside the first few pages a reference to the
translations of the Bible they have made into 27 languages. The second
example they give is to the Arabic language of the passage in the New
Testament from the Gospel of John 3:16. The verse begins in English;
"For God so loved the world.." and in the Arabic translation the word
used for "God" is "Allah."
The Arabic Bible beginning with the Book of Genesis uses the word
"Allah" to represent "The God" of Creation; Adam and Eve; Noah; Abraham;
Ishmael and Isaac and Israel. Page one of Genesis has the word "Allah"
17 times.