Trump's Muslim ban is causing a lot of outrage. Primarily because he broke Federal Law after firing Attorney General Yates for defying his temporary immigration ban, on the grounds that it was illegal. She was given the boot for actually doing her job and not bowing down to the whim of the President, which is why there's a system of checks and balances in the first place.
It also outraged a lot of people because Trump's ban was specifically for Muslims from countries whose citizens haven't been responsible for the deaths of any American citizens in the last ten years. His ban omits countries who have been linked to US deaths, as well as legal green card holders, which is a huge transgression on the rights over legal dwellers in our country.
The hateful rhetoric against Muslims and Immigrants has fomented to an all-time high, and many are speaking out in defense of refugees.