Is Allah in the Quran the same God as YHWH in the Bible? God in the Bible is not the same character or personality as God in the Quran, and there are significant theological contradictions between them. However, Arab Christians call God Allah, not because they believe Islam has the same God theologically, but because Allah means the (one) God in Arabic. The Arabic-descended Maltese language of Malta, whose population is almost entirely Roman Catholic, uses Alla for “God”. The Aramaic word for “God” in the language of Assyrian Christians is Elaha, or Alaha. A German speaker wouldn’t say ‘God’ either; they would say ‘Gott,’ which is where the English word ‘God’ originates, as English is a Germanic language. Nor would a Spanish speaker say ‘God,’ they would say ‘Dios’ because that is the word for God in Spanish. They are merely the words used to classify a deity, similar to how words like El-Shaddai or Adonai (meaning “the Lord”) in Hebrew function as titles for God, or God Almighty. However, these are not necessarily the name of God, such as YHWH. Likewise, the New Testament is translated from Greek, which uses the word Theos (Θεός) for God. Paul didn’t make Greeks stop saying Theos and switch to Adonia, so I don’t believe Arab Christians must use something other than Allah.

What does the Arabic Bible say? Does it say “God”? No, it doesn’t. In the Arabic Bible, it is written as Allah (اللهُ) because the language is Arabic. Where in the Bible did Jesus say, “to teach all nations, but they have to learn English, Greek, or Hebrew language first?” The Arabic Bibles say, Allah, because of linguistics, not theology. So it makes no sense for them to use a word unfamiliar to their language. It’s like saying we English speakers can’t say “God” because the English Bible is not the original language, and we have to say Adonia. It’s the same argument as, “We can’t say Jesus, we have to say Yeshua/Yahshua, because Jesus is a ‘pagan name’.” An Arab-speaking Christian proselytizing to an Arabic-speaking non-Christian will say, “Yasu (or Isa) is the Masih” (Jesus is the Christ), and that is biblically correct because the language has the same meanings as the Bible.

In Arabic, Jesus’ name is “Yasuʿ” (يسوع), which is what Arabic Christians call him, although Muslims call him Isa (يَسُوعَ). Yasu is a natural translation of the Hebrew Yeshua. Joshua in Arabic is Yusha (يوشع) and Yehoshua (יהושע) in Hebrew, and Jacob is Yakub (يعقوب) in Arabic and Ya’akov (יַעֲקֹב) in Hebrew. So ot makes sense that Jesus should be Yasu in Arabic, just like Yeshua in Hebrew, rather than Isa. Yeshua means “Yah is salvation” or “the Lord saves.” According to Matthew 1:21, he was given this name to Joseph in a dream by an angel because he (Jesus) would save people from their sins. Isa is an attempt in Islam to remove Jesus’ connection to being God in the flesh or “God with us”, by changing the name from “Yah is salvation.”

There are missionary ministries that are translating the Bible into indigenous languages around the world, so is it wrong for new Bible translations to call God whatever word an indigenous culture uses for “god” in their language? Again, the New Testament authors had no problem using Theos because they didn’t maintain Adonia in the Greek translations of the New Testament. Christos (Christ) is the Greek equivalent of the Hebrew “Mashiach” (Messiah). Why do we use Christ, then, if we are supposed to stick with one language?

Any Bible-believing Christian who knows what the Quran says about God’s personality and character would reject it; however, the language of Arabic pre-existed the religion of Islam, so we must not equate the two. Arab speakers were there in the book of Acts 2:9-12 when the Holy Spirit was distributed to those in the Upper Room, so the language of Arabic is not anti-Christ. Islamic theology, on the other hand, is classified as antichrist according to 1 John 4:2-3. We can translate the gospel into other languages for the sake of the Great Commission without compromising it through syncretism with the religions of those cultures. The word “hell” originates from Helheim, the realm of the dead in Norse mythology. Does that mean the English-speaking Christians are practicing Nordic god worship when we say it? No, all the days of the week and the first 6 months of the year in Western European languages are named after Greco-Roman or Norse gods. Every language outside of Hebrew comes with words that have other meanings in other religions; the words themselves are not inherently evil because they are used in different religions. More on the translation of Hell here.

This writing is targeted at Western Christians who say “Allah is not God” as an aggressive phrase targeted at Arab speakers because they assume all Arabs are Muslim. To further my point, English-speaking Westerners involved in New Age pagan practices often talk about “god”, but they aren’t talking about the biblical God. Yet they still use the same word because it is a part of the English language. Should English-speaking Christians stop saying, God?

In conclusion, Arab-speaking Christians are going to use their native word for God, Allah. When people say God in English, they are typically referring to YHWH, the God of the Bible. Ilah is the equivalent of saying “god” (with a lowercase g) in Arabic. However, Allah refers to the God of Abraham. The Arabic word for god is ilaha (إله), but Allah is more like a unique “god” that is distinguished. It’s similar to the difference between the lowercase “g” in “god” and the capital “G” in “God” in the English language. There are no capital letters in Semitic languages; that’s a Western thing. So, they distinguish between any “god” (in generic usage) and “The” God of Abraham by placing an equivalent of “the” in front. The “Al” in Allah can be translated to the word “the” in English. For example, Algebra is derived from the phrase “al-jabr,” meaning “The reunion of broken parts”. It was the name of a book written by Muḥammad ibn Musa al-Khwarizmi, the 8th-century polymath scholar who invented “Algebra” (al-jabr) and also introduced the Western world to Arabic numerals. In fact, his last name, al-Khwarizmi, is Latinized as “algoritmi,” from which we derive the word “algorithm.”

Examples:
Gen 1:1 In the beginning God created the heavens and the earth
Gen 1:1 in Arabic: فِي الْبَدْءِ خَلَقَ اللهُ السَّمَاوَاتِ وَالارْضَ.
Notice it uses Allah (اللهُ) for God, this is from the Coptic bible.

Deut 18:20 But any prophet who falsely claims to speak in my name or who speaks in the name of another god must die.

Deut 18:20 in Arabic:
وَأمّا النَّبِيُّ الَّذِي يَتَجَرَّأُ أنْ يَدَّعِي أنَّهُ يَتَكَلَّمُ بِاسمِي وَلَمْ أُوصِهِ بِشَيءٍ، أوْ يَتَكَلَّمُ بِاسْمِ آلِهَةٍ أُخْرَى، فَيَنبَغِي أنْ يَمُوتَ ذَلِكَ النَّبِيُّ.
Deut 18:20 uses the phrase alihat ukrah(آلِهَةٍ أُخْرَى،) for another god (false god).

Resource:
More info on God for Arabic Christians