Etymology of the Word
The term "Allah" the Almighty is originally an Arabic word, which was used by the pre-Islamic Arabs. They believed in Allah, the Almighty, the supreme God and the one and only God. Some of them worshiped other gods besides Him, while others were polytheists worshiping idols.
Allah's Existence and Attributes
Proper scientific reasoning can be agreed upon as the only way to reach the truth of Allah's existence and attributes by all people (including the believers and the atheists). Since every one agrees that every action has a doer and every thing happens for a reason, nothing can be an exception to that rule; nothing comes out of nowhere and nothing happens for no reason. Examples of that are countless and evident. The entire universe including the living or the inanimate, the static and the mobile have been created from nothing. Common sense and science confirm that if there was some one who had created the universe whether His name is Allah, the Creator, or the Originator, it would not change the fact that the whole universe gives enough evidence to the existence of the Creator.
Studying and following up the Creator's work and products (creatures) is the way to get to know His attributes. For instance, a book signifies the knowledge, experience, culture, style, mentality and the ability to achievement and analysis of its writer. The manufactures give a vivid image and a comprehensive idea of its manufacturer's attributes. If people used this scientific reasoning in their approach to the universe and its creatures, they would be able to see the attributes of the Creator, the beauty of seas, the balance of the universe and the system of its movement, all the knowledge man has reached, nature, the accuracy of cells and the wise reasons behind its details made by the Creator. All of them demonstrate the Creator's greatness, knowledge and wisdom.
Whether people agreed or not upon the wise reasons behind the existence of the universe or the pains and hardships in life, that would not change the result, concluded by the scientific reasoning which confirms the existence of the Great Creator, the Almighty, the All-Knowing and the Wise who believers agree to call Allah, the Almighty.