Everyone knows that Christians, Muslims, and Jews have some long-held disagreements. What is less common knowledge, however, is that the three Abrahamic religions stem from from a single text: The Torah, otherwise known as the Old Testament.

Christians, Muslims, and Jews have a common belief in The Old Testament's legitimacy. Moses, perhaps its most important figure, is revered by each of the creeds as being a prophet of the one true God. 

The real conflict stems from what came after Moses: the prophecy of a Messiah, a prophecy that would ultimately result in the greatest philosophical fissure known to man.

"And there shall come forth a rod from the stock of Jesse, and a branch shall grow from his roots; and the spirit of the Lord shall rest upon him... and he shall strike the earth with his mouth, and with the breath of his lips he shall slay the wicked."

- Isaiah 11:1-4

Christians believe that Jesus Christ was this Messiah while Muslims believe that Mohammad was the Messiah. Jews do not believe that the Messiah has been born, but that he is yet to come. Of course, in our modern day this is only a drop in the ocean and there are a myriad of differences between the three doctrines.

However, Christianity and Islam would not exist at all had the aforementioned not been prophesized. 

Who the Messiah is (and isn't) became the original disagreement that birthed centuries of conflict, as well as dramatic cultural divergences. It is difficult to find a war in which one of these three religions did not play a major role, and it is difficult to find any society that is not influenced by them in a significant way.

Yet despite the modern complexity of the battle between Judaism, Christianity, and Islam, the Messianic issue is simple enough to understand. It all began with the birth of a baby boy.

Around 2,000 years ago Jesus Christ was born, a descendent of the line of Jesse. He lived a quiet life for thirty years until preaching the word of God, claiming to be the son of God himself. Unlike the previous Testament that describes the rule of the Lord as harsh and unforgiving, Jesus preached mercy and forgiveness. 

The best example comes from the classic tale of the adulteress. 

Whereas the Old Testament dictates that adulterers shall be put to death - usually by stoning - Jesus had a very different thing to say to the angry mob that held an adulteress captive.

"He that is without sin among you, let him cast the first stone at her."                                                                                                                                                    - John 8:7  

Jesus's "revised" teachings were compiled into the New Testament. Those who believed him to be the Final Prophet and son of God became Christians. Those who rejected his teachings and continued to follow the so-called "Old Testament" remained followers of Judaism. Of course, they do not call their scriptures the Old Testament. What is known as the Old Testament to Christians and Muslims is referred to by Jews as the Torah.

This is how the New Testament and Christianity entered the religious arena. 

But what about Islam? 

Surprisingly enough, Islam, unlike Judaism, accepts the moral teachings of Jesus Christ as being divinely inspired. The major problem is that it does not accept Jesus Christ as being the son of God or the Final Prophet. According to Islam, Jesus was just another prophet. And as was the case with Moses, the law preached by Jesus could be superseded by another. 

This is where Mohammad comes in.

Mohammad was born in 570 AD, and he is revered by Muslims as the Final Prophet. Whereas Moses was replaced by Jesus and Jesus was replaced by Mohammad, according to Islam there will be no more prophets after Mohammad. In other words, their word is final.

The teachings of Mohammad, believed to have been revealed to him through the angel Gabriel, were compiled into the Qur'an. Though the Qur'an comes after the New Testament, it is much more similar to the Old Testament. The stories of Moses play a very important role in the Qur'an, and the law, or Sharia, that it outlines are often direct reflections of the law from the Old Testament.

Lets take another look at fornication, one of the most infamous sins in any of the three religions.

"The fornicatress and the fornicator, flog each of them with a hundred stripes. Let not pity withhold you in their case, in a punishment prescribed by Allah, if you believe in Allah and the Last Day..."
                                                                                        - Qur'an 24:2                                     

Obviously, this comes as a far cry from the New Testament's teachings of mercy, but holds a close similitude to the Old Testament's style of punishment, which prescribes little mercy for sinners and especially adulterers (Leviticus 20:10).

This comes as an unusual paradox: Islam rejects Jesus Christ as the son of God, agreeing with Judaism on this point, and yet accepts that Jesus was indeed a prophet, agreeing with Christianity. Yet despite the fact that they accept the legitimacy of Jesus's teachings of mercy and the reversal of the old law, they believe that Mohammad as the Final Prophet reenacted the punishment-style of the Old Testament. 

A bit of a brain teaser, huh?

Completely understanding the differences between Christianity, Judaism, and Islam would take a lot of work and time, if such a feat is even possible. However, to hold a basic understanding of where their differences arose, one must only understand the Messianic issue. Not only is the Messiah the root of the issue, but he is also the root to developing an intimate knowledge of the most influential religions in the world. 

Hopefully we can all agree on that.

Best Books for Understanding the Religions

In order to comprehend the differences and similarities of the Abrahamic religions, one must first understand each religion by itself. Besides the obvious core texts, here are the best materials for doing so.

Christianity:

The Life of Christ, by Fulton J. Sheen.

Before putting your intellectual trust into a book, you must first understand who, exactly, wrote it. Fulton J. Sheen was an American bishop of the Catholic Church who had an influential presence on both radio and television. In other words, this book describes the life of Christ in a very spiritual manner and is not the most objective material on the subject. However, upon reading the book I gained an intimate understanding of Christian attitude toward this important historical figure. While I did learn plenty of objective facts, I mainly learned the spiritual basis of many Christian beliefs. I highly recommend The Life of Christ for this reason.

Church History in Plain Language, by Bruce Shelley.

The author of this book was a professor in church history and historical theology. Not only does Shelley provide an objective view of Christianity's evolution, but he accomplishes the impossible feat of providing it in an easy-to-read manner. Church History in Plain Language was not created for the learned theologian but for the everyday person hoping to better understand this religion.

Judaism: 

Essential Judaism: A Complete Guide to Beliefs, Customs & Rituals, by George Robinson.

Robinson wrote this book due to being confused by the various customs of his synagogue. He does not focus on the history of these customs but delves into their deeper meanings, making Essential Judaism the perfect book for a spiritual understanding of Judaism.

A Short History of the Jewish People: From Legendary Times to Modern Statehood, by Raymond P. Scheindlin.

Similar to Bruce Shelley, Scheindlin is a scholar of Hebrew literature and provides an objective view of Jewish history. Not only does he do so in an easily readable fashion, but the book is a rather quick read for its sort: only 288 pages! I definitely recommend A Short History of the Jewish People for those looking to gain a basic and secular perspective of the forces that shaped modern Judaism.

Islam: 

The Life of Muhammad, by Ibn Ishaq and translated by Alfred Guillaume.

This book is a long read. I have to start with that. But there is no book more necessary when it comes to understanding Islam. Unlike Judaism and Christianity, Islam centers upon emulating its founder in every possible way... even growing one's beard in the fashion of Muhammad is highly encouraged, and sometimes even enforced. The writer of this book himself viewed Muhammad as the perfect human being, but do not let this put you off. This book neither demonizes nor puts sprinkles upon Muhammad, put describes his life in an completely unflinching way. Though there are shorter and less comprehensive versions of Muhammad's life out there, I definitely recommend putting in the extra work. If you wish to understand Islam, reading The Life of Muhammad is essential.

Destiny Disrupted: A History of the World Through Islamic Eyes, by Tamim Ansary.

Though Ansary's main career is as an author and public speaker (and so his works must be taken with a grain of salt), Destiny Disrupted is a great read for those wishing to understand both the past and modern conflicts between the Muslim world and the West. It is not a completely objective work of Islamic history but provides many insights and analogies that make it relatable and engaging. I recommend this book for those who aim to better comprehend the tumultuous modern events related to Islam.