About Allah (SWT)

From Sahih Bukhari, Volume 9, Book 93, Number 469:
Narrated Ibn Abbas:
When the Prophet sent Muadh to Yemen, he said to him, "You are going to a nation from the people of the Scripture, so let the first thing to which you will invite them, be the Tawheed of Allah. If they learn that, tell them that Allah has enjoined on them, five prayers to be offered in one day and one night. And if they pray, tell them that Allah has enjoined on them Zakat of their properties and it is to be taken from the rich among them and given to the poor. And if they agree to that, then take from them Zakat but avoid the best property of the people."

"[Faith] in One God is the most important and fundamental principle. It is the bedrock of Islam and the mainspring of its power. All other beliefs, commands and laws of Islam stand firm on this foundation. All of them receive strength from this source. Take it away, and there is nothing left of Islam."
- Abul A'la Mawdudi, Towards Understanding Islam, Islamic Foundation, 1980

"The Islamic interpretation of monotheism is more literal and uncompromising than that of any other religion. Allah is confessed as being one, eternal, unbegotten, unequalled, and beyond partnership of any kind."
- The New Encyclopaedia Britannica, 15th edition, 1992