Heres a quick explaination of Islam for you .
If an extremist read the quaran in its true form , then followed its revelations to the letter he has no choice but to act with violence against the Kaafir , the labels Infidel , Kaafir & Kuffer represent 3 different groups of people in the quran with the Kaafir being the most loathed because he has been given the words of Islam , he understands the laws of Islam & he rejects Islam , another person who is a Kaafir is anybody who has taken up arms against Islam ,Kaafirs have no chance to repent & are supposed to be killed immediately, Infidels are non believers & are given 3 days to reflect on their blasphemy before death or imprisonment occurs, a Kuffer is a Jew , a Christian or anybody who believes in the holy trinity , infact over 60% of the quran speaks about how a muslim should deal with or interact with non believers of Islam ,early revelations in the quran speak of peace & acceptance of jews & christians while later revelations speak of shunning & violence twords the Kaafir , well thats great because all the people who swear Islam is a peacefull religion conveniently leave out one very important issue which is Abrogation .
Abrogation is the interpretation of conflicting verses in the quran where one verse seeks the approval & acceptance of the jews & christians while another verse condems the jews & christians then urges war against them , Abrogation rules that the verse laid out 1st chronologically ( Not as laid out in the qurans non linear form ) will be cancelled out by any chronologically later verses covering the same subject .
In the chronological timeline of the quran Mohammad calls for peace with other religions in the beginning , the further along chronologically the more violent Mohammad becomes when explaining on how to interact with Kaafirs , Infidels & Kuufers , the quran is a non linear book with its chapters laid out in non linear form & follows no real timeline .
The quran is a long confusing read because its out of chronological time frame & talks about situations & the same people dozens of times , i think Moses is covered like 20 times & saying the same stuff each time he's spoken about, if you want to understand the quran you can buy a condensed version which deletes the hundreds of pages speaking about the same people like Moses & Pharrow , it also puts the quran in a linear chronological time line making it much easier to understand Mohammeds words in how Muslims are urged to interact with all 3 groups of undesirables spoken of in the quran .
The most important thing when buying a quran is to buy a revised version which puts chapters & verses in their true chronological order , read that then you can argue Islam with these guys till the cows come home .