Warner founded the Center for the Study of Political Islam (CSPI) and is its director. His stated aim is to make Islamic doctrine, particularly the political and legal system of Islam, understandable to any member of the general public, and his training in scientific theory and mathematics has "shaped how he analyzed Islamic doctrine".
His books focus on Islamic law, and the canonical texts from which that law is derived. He uses these Islamic texts (Qur'an, Sira and Hadith) as his primary sources of evidence, draws his conclusions from them, and quotes from them copiously.
He considers the life of Prophet Muhammad as the key factor in understanding Islam and how it should be practised, “To know Islam, you must know Mohammed. His life, called the Sira, and sayings, called Hadith, are the foundations of Islam. It is more important to know Mohammed than the Koran. Our books will show you one of history's interesting leaders”.
According to Warner, there are two key principles that underlie Islam’s political system: duality (particularly moral dualism) and submission (to the hierarchies Islam imposes).
"Sharia Law for non-Muslims" - Pages: 48 Release Date: June 6, 2010 ISBN: 978-0979579486
Islam has its own separate legal system (Shari'ah), derived from its canonical texts. “Sharia is the Koran and Sunna interpreted by Islam’s ﬁnest scholars”. It is Warner’s opinion that “The easiest way to learn about Islam is through Sharia law”: he believes that by studying Shari'ah, the reader will come to understand Islam in a “practical manner”.
Warner’s main intention is to explain the consequences of this legal system when its laws are applied to non-Muslims and when its influence extends into non-Islamic societies. “Sharia holds two sets of laws—one for Muslims and one for Kaﬁrs [non-Muslims]. Kaﬁrs are not treated as equals, but as inferiors. This is legal dualism”, which results in different rights, responsibilities and penalties for Muslims and non-Muslims; also “The principle of submission comes into play. Kaﬁrs must submit to Sharia in all matters”. Regarding the imposition of Shari'ah in non-Islamic nations, the author gives a list of examples from America and Europe. Warner states: “There are no common principles between American law and Sharia”.
He emphasizes that “when you understand its principles, Islam is very, very logical. It is based on different views of humanity, logic, knowledge, and ethics” and “Once you understand the principles and logic, you not only can explain what and why something is happening, but you will be able to predict the next step in the process”. All the information provided is referenced for the purposes of objective examination: “Everything you see here can be independently veriﬁed.”
On the subject of legal reform within Islam the conclusion is: “Sharia cannot be reformed. It is Allah’s law and it is perfect, universal, complete and perfect”.
There are fourteen chapters covering a wide range of topics such as Family law, Jihad, Slavery and the Freedom of ideas. The scope of the material is such that, according to the author, “When you ﬁnish reading, you will know what Sharia law is.”