There are indeed some verses in the Koran that sound very liberal, tolerant and peaceful. The trouble is, there are other verses that contradict them. And, using the well-established “doctrine of abrogation” it can seriously be argued by militant Muslims that the liberal, tolerant verses have actually been “abrogated” or repealed by later, more intolerant verses.
Two of the wild cards that make it almost impossible to answer your question in any brief manner are the doctrine of abrogation in the Koran, and the problem of interpretation.
The doctrine of abrogation is not something I made up. It is a well-known concept in Islam. See this articleor google it yourself.
One thing you should know about the Koran is that the Surahs are not organized in chronological order but according to length, with the longest first.
It is believed that many of the more tolerant and peace-loving verses were “revealed” to Mohammed when he was first in Mecca, relatively weak and the head of a small, struggling sect. The militant, warlike verses that abrogate them date from after his flight to Medina and from a period when he had become a powerful warrior-prophet able to strike down his enemies.
This is fully admitted by many Islamic scholars who compare abrogation to a doctor who changes the prescription according to the condition of the patient. A weak Mohammed received “tolerant” verses. When he was stronger, Allah gave him warlike verses to replace them.
I will give one rather long example. Multiply that by 1000 and you will get an idea how impossible it is to discuss Koranic interpretation rationally with a devout Muslim. It is like shadow-boxing with Jello.
For example, there is a verse often quoted by Muslims who want to show that Islam is not an agressive, intolerant warrior cult, that says “There is no compulsion in religion.” (Sorry, I do not have the exact Surah and verse numbers for that one).
There is also what sounds like a very open-minded attitude towards Christians and Jews in Surah 2, verse 62, which says: “Those who believe (in the Quran) and those who follow the Jewish (scriptures) and the Christians and the Sabians, - Any who believe in Allah and the Last Day, and work righteousness, shall have their reward with their Lord: on them shall be no fear, nor shall they grieve.”
Sounds pretty broad-minded, at least towards other monotheists, right? But then, how do you square this with Surah 3:85?:
“If anyone desires a religion other than Islam (submission to God), never will it be accepted of him; and in the Hereafter he will be in the ranks of those who have lost (All spiritual good).”
Also contradicting the concept of tolerance is Surah 9, verse 29, which says:
“Fight against such of those who have been given the Scripture as believe not in Allah nor the Last Day, and forbid not that which Allah hath forbidden by His messenger, and follow not the Religion of Truth, until they pay the tribute readily, being brought low.”
By the way, for those of you who insist on context in every case, look at verses 30 and 31 that follow the above verse and you will see that it the Koran is quite certainly speaking of the treatment of Jews and Christians here.
The “tribute” referred to is a special tax (jizya) that had to be paid by Christians and Jews in Muslim lands for right not to become Muslims. These people were called Dhimmi and if you research that term in Wikipedia you will find the interesting quote: “It is claimed that Dhimmis, unlike the Jews and Muslims of reconquered Spain, did not have to choose between apostasy, exile and death. However, the choice of death or conversion was often the de facto reality for those Dhimmi who could not afford to pay the jizya, many of whom faced death or torture because their impoverished circumstances did not allow them to pay.”
Those who did pay the tax were subjected to a tax-collection ritual in which the Muslim tax collector grabbed them by the beard and slapped their face as he collected the tax, as part of the ritual of ensuring they were “brought low”. Cordoba, Spain, after which the ground-zero mosque is to be named, witnessed many such atrocities in this alleged city of interfaith harmony.
So now, interpretation kicks in. For example, how is it possible for 78% of Pakistani Muslims (PEW Research) to say that apostates from Islam should be killed if there is “no compulsion in religion”? Simple!
Being humiliated, slapped, and extra-taxed do not “compel” you to join Islam, now do they? If you join, you join “voluntarily” even if there was a lot of “incentive”.
But what about murdering people who choose to leave Islam? How can that be “No copulsion in religion”? Simple! You can either claim that the earlier, tolerant verse about compulsion was “abrogated” or else you can claim that the verse still stands, but that it simply means you cannot be forced to enter Islam. But attempting to leave Islam is not covered by the “no compulsion” verse.
Sorry for this long-winded answer, but hopefully, you will see how difficult it is to accurately answer the question in the OP.
If you judge Islam by its history and by the vast number of warlike verses in the Koran, the long and the short of it is that Islam is a warrior-cult founded by a warrior-prophet that believes in the concept of holy war and violence to bring the whole world to the worship of Allah. If Islam can be spread without violence (eg. the Muslim birth-rate in Europe), sine. But war and violence are never ruled out. It is an ideology that rejects all concepts of secular freedom and the rights of the individual as we understand them in the west. Moderate Muslims are usually simply lukewarm or lapsed Muslims who still pay lip service to the religion of their parents.