Allah, the Arabic word for the One True God, is unique in that it can have no plural or gender connotation. A muslim believes in one, unique, incomparable God. God has no son, nor partner. No one except Allah has the right to be worshipped but him alone.
God alone is the Almighty, the Most Merciful, the Creator, the Sovereign, and the Sustainer of the universe and what lies beyond it. He is the Eternal. He manages all affairs. He stands in needs of none of His creation, yet all are in need of Him. He alone is Independent. He is All-Hearing, the All-Seeing, and the All-knowing. To Him alone belongs Perfection and His alone are the most Magnificient names and the perfect attributes. His knowledge encompasses all things.
“None has the right to be worshipped but Allah” is the testimony that is the centre of Islamic religion and its followers.
According to Islam, whoever says La ilaha illa-Allah sincerely will enter paradise.
Allah can not be seen and can not be worshipped using any idols. In Quran, the holy book of Islam, It is said that Allah has ninety nine names. All of them are holy and speak about different attrributes of the same creator, the almighty Allah. As an example, read these verses of the Quran:
[Allah is He, than Whom there is no other god; Who knows (all things) both secret and open; He, Most Gracious, Most Merciful.
Allah is He, than Whom there is no other god; the Sovereign, the Holy One, the Source of Peace (and Perfection), the Guardian of Faith, the Preserver of Safety, the Exalted in Might, the Irresistible, the Supreme: Glory to Allah! (High is He) above the partners they attribute to Him.
He is Allah, the Creator, the Evolver, the Bestower of Forms (or Colours). To Him belong the Most Beautiful Names: whatever is in the heavens and on earth, doth declare His Praises and Glory; and He is the Exalted in Might, the Wise.]59:22-24