There seems to be one commonality between polarizing politics, terrorism, and war: poverty.
We have been fighting poverty in the U.S. for over 50 years and despite pouring trillions into the effort, the number of people living in poverty is higher. It is futile effort. Since a majority of people living poverty support Democrat politicians it is the goal of Democrat politicians to make sure people are perpetually living in poverty and dependent on the government. Why? Because there is a good chance once a person leaves poverty they may no longer support Democrats. This assures they will continue to garner the poverty vote. That is an important point, people living poverty tend to be dependent on others and do not act and or think for themselves. Hence, poverty stricken people are easily manipulated and brainwashed.
We see the same types of strategy when we look at terrorists. Many people recruited to be a terrorist are poverty stricken. They are easily brainwashed via propaganda into believing anything for any cause as long as those in charge make them feel important. So a person is willing to be a suicide bomber so long as they feel important and they are fooled into the adage that they making a difference in the world. In other words, terrorists are looking for a cause.
War is not much different than terrorism. Where is there is terrorism and violence there is usually war. Throughout history there have been many revolutions where the poor masses revolted against the privileged ruling class. Hitler was great at using propaganda to brainwash the masses into war. After all, at the time, Germany had a massive poverty problem. Therefore, it is not surprising World War II happened during the Great Depression. This is a time when people are desperate and would cling to any hope in any message.
The bottom line is that poverty presents several variables that makes it ideal for advancing polarizing politics, terrorism and war: Dependency, Desperation, and Brainwashing people into believing they are an important variable in a righteous cause.