This book aims at presenting the most basic knowledge of Islamic Creed (Aqidah). Unless a persons creed is in accordance with the Noble Quran & Sunnah of Prophet Muhammad (PBUH), his good deeds can be at risk. Hence, this type of knowledge can never be optional. Purity of intention, how to believe and what to believe, and love of Allah -- are all matters of belief of creed, whereas the acts of worship like Zakat, Salat, Hajj and Fasting are deeds that may be counted positively only if the belief aspect is correct. Priced economically, this book is a must-read for all.
Other Sources:
There is no God worthy of worship but Allah - Quranic verse
There is only one God (Allah) not multiple gods - Surah Al Anbiya Verse and Ayah 22 Quran