*Disclaimer: I feel the need to say that despite my research and questioning, I still do not know everything there is to know about Islam. Rather obvious, but because of my ignorance, my perspective/understanding may be slightly skewed.*
Islam is a religion. Muslims are the followers of Islam. Shari'ah is the body of Islamic law, which describes the laws set forth in the Qu'ran. Jihad means struggling or striving (towards the will of Allah), and from this aspect of Islam, terrorism is understood.
In modern-day America, our lives have become inundated with religious stereotypes fueled by news regarding acts of terrorism. There most certainly is a connection between Islam and some of these terrorist acts, but one thing is also certain. Not all Muslims are terrorists. Nor are all terrorists Muslim.
Islam, like Christianity, has a religious doctrine. Compiled in the Qu'ran (literal meaning: recitation), followers of the Islam faith are told how to live their lives according to the will of Allah (God). God is the English word for Allah. Though most Muslims would argue they are two different ideas/entities, our monotheistic views are similar. The word of the Qu'ran is unlike the Holy Bible, however, in that Muslim's believe it is the direct word of Allah, simply spoken through Muhammad. Muhammad was said to be the last prophet of Allah sent to restore Islam, and through Muhammad, Allah supposedly sent everything in the Qu'ran. Muhammad did not write the Qu'ran however. Instead, the followers of Muhammad compiled the Qu'ran which they had memorized by heart.
The Qu'ran contains several startling verses, but like so many other religions, interpretation is the variable. Not all Muslim's agree on the violent nature of Islam depicted in some translations. Some practicing Muslims disagree only with certain aspects of a particular interpretation and as such reject certain doctrines in said interpretation. The origin of the religious stigma against Islam stems from those Jihadist extremists who take the word of the Qu'ran at face value, and fully aspire to fulfill their violent "duty."
While I am certainly no religious scholar, it is my understanding that the doctrine of the Qu'ran both allows and encourages violent acts of terror against the "infidel." There is a stipulation to this however, which says that such violence should never be initiated by a Muslim. Instead, any act of violence should only be defensive and to save Islam. Those Muslims following the peaceful side of Islam may one day face the realization that to be a true follower of Allah, they too must "struggle against the infidel."
A possible explanation for increased terrorist activity is that Jihadist groups may be considering things we do not view as offensive as such. In this case, the horrible events we have seen throughout history (including 9/11, the attack at Chattanooga, and the more recent attack in San Bernardino, CA) were initiated because those terrorists believed it was the Jihad duty to "strive and struggle" towards Allah.
I have met and connected with several people belonging to the Islamic faith. I cannot comprehend how a society can associate an entire religion with terrorism. Religion is very much interpretation-based. As such, Islam is not the source of terrorism. Nonetheless, Islam does provide ample opportunity for followers to rationalize terrorism through the Qu'ran. Whether those committing acts of terror are truly led by their violent interpretation of Islam, or just are just using the stigma against Islam to their advantage to cause more chaos in the world, I can only speculate.
One could argue all religions have plenty of opportunity for violent interpretation. There are extremists in every societal aspect. Religion, politics, you name it. These extremists may be willing to die for what they believe. It just so happens that some Islam extremists believe it is their religious duty to kill the infidels. Can this be allowed? Absolutely not, it goes against the Universal Declaration of Human Rights (though in 1990, these rights were stipulated under Islamic Shari'ah). Should we immediately mark off all Muslims as terrorists? Absolutely not, but I still remain uncertain how any peaceful interpretation could exist that so vastly contrasts the violent perspective that has become recognized as the Islamic standard.
The line between terrorism and Islam is becoming thinner by the day. As Chattanooga shooter Mohammad Abdulazeez said, the terrorists we see in the news may be going against Islam entirely, using the guise of radical Islam to shadow their acts of terror. Regardless, I believe we must realize that generalizations made regarding something based on interpretation (such as religion) are not easily made. Terror is terror and it does not discriminate. If terrorism truly is connected to the Islamic religion, then Islam itself must reform. Otherwise, we are in for a long millennium.