It is very obvious that Islamic religion/ people kill many Christians all over the world. Although the Bible says, do not murder, they still practice it. What would be the reason.?
The reason is, because their religious writings require it. See:
https://www.thereligionofpeace.com/pages/quran/violence.aspx.
You will hear a lot of Muslims and Muslim clerics say that violence is not what the Koran is talking about when it says to do violence. They will say it is only self-defense. And they are right from their standpoint.
Muslims are supposed to be peaceful towards other Muslims. If the whole world was Islamic, there is supposed to be peace. But there is very little peace toward people of other religions/governments. Yes, Islam is a government as well as a religion.
The whole Islamic religion is about making money. The Islamic leaders make money off the tithes that the Muslims pay. You can't make money if there is fighting and strife. You can't make money if people are paying it to other governments and religions. There is no peace if you can't get all the money.
This is why the clerics talk peace, when the Koran and Hadiths say violence. No money in it for the Muslims.
One of the greatest areas of Muslim violence is when a Muslim doesn't obey the laws of Islam... when he/she turns to a different religion. If your Muslim brother or sister turns away from Islam, you are required to execute him/her. And the execution should be on the spot, right now, if they are raddically against Islam.
This makes Islam a religion of fear, because you never know if you are good enough in the sight of your fellow Muslims. You are always afraid that they will find something wrong with you, and execute you on the spot. This fear is what keeps the Muslim community together, and keeps Islam strong.
But the strength is for the Muslim leaders and clerics, who get the money.
Nowadays most Muslims are peaceful towards their fellow Muslims, and towards the rest of the world that is not Islamic, because they don't realize that Islam tells them to be violent against people who are not Muslim. But they can turn violent on a moment's notice if their clerics order some Muslim zealots to stir up the community against someone.
You might be a Christian living peacefully among peaceful Muslims. You might have been living among them peacefully for a long time, even decades. Then, suddenly, a cleric takes a disliking for you, and stirs up some Islamic zealots. They form a mob out of some peaceful Muslims - even your close friends - and they kill you. Your friends take part, both out of fear for their god, and out of fear of the Muslim community.
ISIS is an example of Muslims obeying the literal Koran. ISIS is doing what all Muslims should do if they are real Muslims. ISIS is peaceful toward other members of their group, and toward most other Muslims. Sure, they make their mistakes. But they are obeying the literal Koran rather than the lying clerics.
Islam is a religion of fear and violence. It is NOT a religion of peace.