I recently posted an article entitled “The Ease and Simplicity of Islam“. It was actually one chapter of a booklet I wrote but did not publish yet, “Top Ten Reasons why I love Islam”. In the next chapter, I explored the other perspective, which is also a major reason why I love Islam, its depth and vastness in terms of knowledge:
Despite Islam being a simple religion to understand and practice, it is at the same time very deep for those who love intellectual pursuits. Islam caters for all types of people, as a result it is simple in the basics, yet for anyone who wishes to learn more, the sciences of Islam are so many and so deep that you can study them all of your life without running out of books and topics to study.
Islam is the ultimate gift for those seeking intellectual challenges. It is so deep that the knowledge of Islam is often described as an ocean without any shores. Islam has many sciences to choose from in your studies, perhaps you would like to study the Aqeedah (belief system) of Islam in depth. This would include studying the many books on Tawheed, prophethood, the after life, angels, jinn and destiny, as well as the deviant sects, their beliefs and refutation. There are many books on each of these topics, some basic that all Muslims must read, and others in more details for those who want to learn more.
Perhaps you would like to understand the Qurʾān better. This would mean studying the many books of Usool-Tafseer (principles of interpretation), the many translations of its meaning and the many books of Tafseer (interpretation). Again, the basic message of the Qurʾān is simple and easy for anyone to understand, yet if you study all these fields, you will keep discovering more and more depth in the meanings of each verse.
Perhaps you would like to study the hadith in detail. This would mean learning the Usool-Hadith, learning which hadith are weak, fabricated and which are authentic, studying the many books of hadith and the many books explaining them. There are thousands of hadith, and sometimes you will find entire books explaining just one hadith! Again, hadith are generally short and sweet and easy to understand, yet they can be very deep for those who wish to explore their depth even more.
Perhaps you would like to study Fiqh (Islamic law) in detail. This would mean studying the Usool-Fiqh, the many opinions on each issue, the different dimensions and situations involved, the relevant hadith and Quranic verses and to figure out the strongest opinion on each issue. The study of this area can consume your entire life, yet the basic knowledge of this science can be found in just one or two books, however it can get very deep for those looking for a challenge.
Perhaps you would like to study Islamic history in detail. You can study the lives of so many prophets, companions and great Islamic scholars and personalities and learn from their beautiful examples. You can also study the history of the Islamic civilization and its impact on science and education. You will not find any other religion, which has so much information about their prophets and heroes. The books of Islam can teach you minute details about the Prophet Muḥammad's (peace be upon him) life, physical descriptions and mannerisms, as well as deep lessons learned from all these things.
As one can see, there is so much to learn about Islam, Islam is simple and easy to practice for the average person yet so deep and amazing that you can never run out of things to study. It is this depth that attracts many intellectuals to Islam.