This book is talking about the Correct Belief & what Contradicts it (in Spanish Language)

Este libro habla de la creencia correcta y lo que la contradice.

This book is a brief yet extremely beneficial explanation of Shaykh al-Islam Muhammad ibn `Abd al-Wahhab's famous Kitab al-Tawhid. The book, as the title suggests, deals with the subject of worshipping Allah alone without associating partners with Him. The author highlights many matters that have become common among Muslims even though they are clearly acts of shirk or associating partners with Allah. Not only is this book distinguished due to the importance of the subject matter but also due to the methodology adopted by the author for which he is well known. The reader will find that the majority of the book consists of verses of the Quran, ahadith of the Prophet ( ) and sayings of the early Muslims. The explanation presented at the end of each chapter of Kitab al-Tawhid is that of the renowned scholar

About Shaykh Abu Abdu-r-Rahman Nasir As-Sa'di

Allamah Abd Al-Rahman Nasir As-Sa'di born in the city of Unayzah in al-Qasim Saudi Arabia, he was a prominent Islamic scholar, jurist, exegete, and Arabic grammarian with a great interest in poetry who contributed many works on a variety of subjects. from a young age became engrossed in the attainment of knowledge. His dedication and thirst for knowledge led him to become an authority in many of the Islamic sciences as is evident from the books that he authored. Initially, he adhered to the Hanbali school of Islamic law (madhab), as did his early teachers. He went on to study the works of Ibn Taymiyyah (d.1328) and Ibn al-Qayyim (d.1350) extensively, and, as he progressed in his studies, he no longer restricted himself to the Hanbali school, but rather followed the course he believed to be proven by the strongest evidences. He was also an expert in tafsir (Quranic exegesis or commentary), having read many books of tafsir and studied it under his teachers; he later authored a tafsir himself.
as-Sa'di died at the age of 69 on a Thursday in the year 1956 (1376 AH) may Allah have mercy on him.

This work draws heavily on arguments set forth in the Holy Qur'an and Sunnah, including arguments that refute the views of sects that have deviated from the Sunnah of the Prophet (peace be upon him).
Moreover, this book contains references to views of the Shi'ah, Khawarij and mystics that have departed from the right path.
English and Arabic text.

Although the vast majority of mankind believes in a Creator or Supreme Being, their concepts vary. Islam, in the Qur’an and sunnah, affirms the existence and Oneness of the Creator and describes Him as having the most perfect attributes, thus enabling man to have the proper concept of Him and to establish a strong bond with Him based on the understanding of His sublime attributes. But the influence of philosophy and other ideas that are alien to Islam led to the emergence of distorted concepts about Allah.
In this book, Dr. ‘Umar S. Al-Ashqar discusses the wrong ideas that have crept into Muslims’ minds concerning Allah and His attributes, and highlights the fact that the only correct way to understand the verses of the Qur’an and the Ahadith, which speak of Allah and His attributes, is the way in which they were understood by the first generations of the Ummah (the salaf).
Dr. ‘Umar S. Al-Ashqar also examines modern concepts, such as the theory of evolution, and proves that they are wrong and false. Following the Qur’anic injunction to ponder the signs of Allah in the universe, he also pays attention to the study of natural phenomena which clearly point to the existence and Oneness of the Almighty Creator. Thus, Dr. ‘Umar S. Al-Ashqar affirms the principle which lies at the heart of the Islamic faith and practice, namely Tawheed, the Absolute Oneness of the Divine.