God Is Allah Is God
It is actually quiet simple. Allah is the Muslim name for the Christan God and God is the Christian name for the Muslim Allah. Allah and God, God and Allah both one and the same. Jews, Christians, Muslims are all people of the 'Book'. They all believe there is only one God. They all believe in the same God. The only real difference is the name they use and the interpretations of his word.
The French don't use the word God....they use Dieu.
The Maltese, a devoutly Catholic country don't use the word God....they use Alla.
Jews, Christians and Muslims all follow different paths but all share the same God, the God of Abraham. Within their defined religions there are numerous sects following different interpretations of their shared beliefs.
Muslims
Most people are familiar with the fact that there are Shia and Sunni Muslims. Fewer are aware of the fact that there are a number of other sects which have different interpretations of their shared Islamic religion.
They also share the belief that there is only one Allah. They believe in the one God.
The Koran, the word of God actually says of Christians and Jews in in Sura 29.46 "Our Allah and your Allah is One."

Christians
There appears to be an almost endless number of Christian demoninations. Catholics, Protestants, Greek Orthodox, Russian Orthodox, Syrian Orthodox, Lutherans etc etc
Each has its own interpretation of the 'word' but all believe in one God. They all believe in Allah.
The language of Jesus was Aramaic. The Aramaic word for God is Allaha. Don't forget that Jesus was a Jew and is also a prophet of Islam.
It has been suggested by Bishop Martinus Muskens of Breda in the Netherlands that Christians call God, Allah as a way of promoting better relations with Muslims. After all if it was good enough for Jesus?

Jews
As the longest established of the three it is no surprise that it has been divided into numerous sects and subdivisions and denominations each with its own interpretation of the book.
The Jews believe in one God. They believe in the God they share with the Christians and the Muslims.

Interpretations, misinterpretations, re-interpretations, angles, slants, points of view all differ when it comes to language and religion. The above is mine. I am not a Muslim, Christian or a Jew. May my Gods bless you all.

