Added 1.5.16; edited for clarity and concision 7.28.23
Is al-Qur'an 4:101 really calling non-Muslims "open enemies"? And doesn’t 8:12 say to kill the "infidels"?
Both revelations specifically refer to circumstances going on at the time of Prophet Muhammad ﷺ, and they only apply to such circumstances. The people of Makkah, the Quraysh, had turned the Ka’bah into a place of idol worship as part of their economy, driven and provided prestige via visiting pilgrims. It had been built by Ismail and Abraham, peace on them, and, to this day, it's still on the same foundation at the center of Masjid al-Haram. Back in the 7th century, When the Prophet Muhammad ﷺ came with a revelation saying to worship none but Allah, and especially when people started following him, the Quraysh objected. They did not want competition for their way of life and the religion of their forefathers or the various idols they were known for. So, they persecuted those early Muslims. They tortured, killed, lied about, and boycotted them. The boycott, in particular, went on for three years wherein the Muslims were cast out of their homes and were trapped in a valley. At a point, they resorted to eating leaves and camel skin. Eventually, the Muslims migrated north to al-Madinah (Yathrib) to escape that persecution.
Al-Qur'an 8:12, was revealed when 1000 Qurayshi fighters had come to al-Madinah and were descending on virtually the only 300 or so able-bodied Muslim men on the face of the earth. The ayah tells Angels to fight those particular 1000 men coming to kill the Muslims in Badr near al-Madinah. It does not tell Muslims in general to kill non-Muslims in general.
As for the first ayah, 4:101, the reference to "open enemies" relates specifically to disbelievers who fit the condition laid out in the second part of the same ayah, which says, "if you fear that those who disbelieve may disrupt (or attack) you." More specifically, it's about a group of Quraysh who were conspiring to attach Muslims while they were engaged in prayer. Narrated Abu Ayyash az-Zuraqi: “We accompanied the Apostle of Allah at Usfan, and Khalid ibn al-Walid was the chief of disbelievers. We offered the noon prayer. Thereupon, the disbelievers said: 'We suffered from negligence; we became careless. We should have attacked them while they were praying.' Thereupon the verse was revealed, relating to the shortening of the prayer (in time of danger) between the noon and afternoon prayers" (in reference to al-Qur'an 4:101, Abu Dawood 4:1232). Put simply, it's a notice from Allah to those early Muslims that the Quraysh were out to get them and that it wasn't beneath them, even, to attack people during their prayers.
Those who hate and have the desire to harm or kill are enemies their targets, regardless who is on what side. That's what an enemy is. However, that's now how Allah told the Muslims to treat people in general among non-Muslims. Not at all. Rather, "Allah does not forbid you from those who do not fight you because of religion and do not expel you from your homes—from being righteous toward them and acting justly toward them. Indeed, Allah loves those who act justly. Allah only forbids you from those who fight you because of religion and expel you from your homes and aid in your expulsion—(forbids) that you make allies of them. And whoever makes allies of them, then it is those who are the wrongdoers" (al-Qur'an 60:8-9). This is the general, peaceful position Allah ordained for Muslims when they mix with non-Muslims.
But what about when Muslims aren't simply in the mix, but have political position? What then? Even when the Muslims were in governance over a diverse population, the Prophet Muhammad ﷺ said, “Whoever kills a mu‘aahid (a non-Muslim living under Muslim rule) will not smell the fragrance of Paradise, although its fragrance may be detected from a distance of forty years” (Bukhari 2995). In another narration he said that whoever harms such people “harms me and whoever harms me annoys Allah.” In yet another he said, “He who hurts a non-Muslim living under Muslim rule, I am his adversary, and I shall be his adversary on the Day of a Judgment.” The Prophet ﷺ put himself between the other Muslims and the non-Muslims. This way, even the Muslims who hadn't matured in their faith and attached to Allah would understand that the blood of all innocent people is inviolable.
What about the case of military engagement? And the word infadel?
Someone will rightly ask, "But what happens when it comes to violence?" Because it did pretty frequently come to violence during the lifetime of Prophet Muhammad ﷺ, who was a military leader among his other roles. There's no hiding that. His life provides examples for all aspects of life. The rules revealed through the Prophet Muhammad ﷺ are more restrictive in some ways than the Geneva Conventions, and yet there are a few incidents of war that are tough to get perspective on. As a Muslim I do have some perspective on them and trust in Allah given the overall picture. But, I also respect people's examinations of those matters, so I'll talk about them a bit.
As for contemporary absurdities like ISIL or ISIS or apparently ignorant but outspoken influencers like Andrew Tate, those really only deserve to be spoken of when it's either useful in uprooting the nonsense they plant in people's minds or because someone has specific concerns about those things. (I did write about ISIS on my other website and may link that here with an updated version for those interested.) That goes, as well, for 9.11.2001, extreme Muslims movements of all sorts, and whatever else Muslims wrongfully do or say in the name of Islam. I can't present an unequivocal view on modern Muslim military activity among the Muslims who are on the truth, but the view I ascribe to limits the Muslims from doing these things except when under direction, dire threat. That's because there's no khalifah—a leader chosen by discussion and consensus. Things like capital punishment or engaging in battle are things usually ordered in an organized, limited manner by such a leader. In the meantime, many societal-level features of Islam are damaging and can only be misapplications at this time. How I see it, the more fundamental question to get to the bottom of the matter is to ask if those contemporary tragedies and follies are because of the wrongful actions of modern humans or if something about Islam, itself, is leading to that bad fruit. I imagine, right or wrong, that we can agree on that as a starting point to look at this aspect.
I'll admit that in some circles and literature (mostly aged), the military legacy of Prophet Muhmmad ﷺ is disparaged as unholy. The Orientalists used the English word infidel, as a translation, presumably, of kaafir. What's so interesting right now is that Marines sometimes refer to both words, but in different ways. The US Marines logo says "semper fidelis," meaning "always faithful." Whereas infidel would be a non believer or one without faith. So some Marines or members of the US Armed Forces put bumper stickers on their cars that say either infidel or the Arabic work kaafir in the actual Arabic script like this: كافر. I take that to mean that they reject Islam, which they can do. However, kaafir in Islam is a more specific term than infidel in any sense.
A kaafir, firstly, may become a Muslim. In that regard, it's not for the Muslims to hate non-Muslims, but only to explain at-Tawheed, the exclusive right of worship, belonging totally to the Creator. All of Islam is predicated on that central reality, and it's something familiar to people, even if the overall lifestyle has become strange for them. Only God deserves to be worshiped, not the false gods people have set up. A kaafir is just someone who has covered that up within themselves, such that their words and deeds follow from that. If kaafir means disbeliever or the one who covers and hides the the central reality, then kufr is the word or action that is upon that. Again, it means to cover something up so that it's no longer visible.
I lived in that condition myself, as did all of the companions of the Prophet Muhammad ﷺ. The Muslims were non-Muslims. Given this whole situation—and the fact that moving from non-Islam into Islam is a trivial matter in the physical sense—it's absurd that Muslims would want to kill, harm, or alienate non-Muslims. That's not to say Muslims aren't quite often repulsive in what they say or do, but it's a combination mostly of ignorance, confusion, politics, and spiritual immaturity. And meanwhile, hopefully, you know many Muslims who are kind and gentle people, looking for the good path to take through life.
The battles of the early Muslims (section still being edited as of July 2023)
The treaty of Hudaybiyyah would allow a temporary peace even between the Quraysh, who were mainly in Makkah at the time, and the Muslims, who were mainly in al-Madinah. A central feature was laying out some means of sharing access to the Ka'bah in Makkah. During the drafting, meaning before anything was signed, the Quraysh demanded the words Bismillaahir-Rahmanir-Raheem (in the name of Allah, the Most-Gracious, Most-Merciful) be removed from the top of the document. The Prophet ﷺ agreed that the words be removed despite protests from prominent companions of his. The Prophet ﷺ also signed treaties with Banu Qaynuqa, the primary Jewish tribe also living in al-Madinah. How I would characterize the situation is that a pre-emptive, defensive mood prevailed among the Quraysh and those particular Jews, though members of both also reverted to Islam.
One prominent case where the Prophet ﷺ had dialoged with the Jews of al-Madinah is when Abdullah ibn Salam converted. Ibn Salam accepted the identity of the Prophet ﷺ because he deemed there a match to prophecies in the Torah. The new convert was prominent among those Jews, to the extent he was a highly respected scholar. He told the Prophet ﷺ to gather the other prominent Jews and to ask them about him. When the Prophet ﷺ did so, the Jews praised him as the best among them. Then, Ibn Salam came out from behind a curtain and testified that none has the right to be worshiped except Allah and that Muhammad is Allah's messenger. The same Jews said that Ibn Salam was the worst of the worst of them.
I'll come back and add more to this section soon, including the major battles after the treaties had fallen apart, and without leaving out the stark events of Khaybar and other moments when many people died on either side of the disputes.
What are the basic rules of engagement if things come to fighting
The Messenger ﷺ forbade, foremost, killing of non-combatants. That comes with much emphasis on safeguarding women, children, and the infirm. Further, when the Prophet ﷺ had fallen ill and died, the first khalifah (ruler of the unified Muslims), Abu Bakr, emphasized specific restraint upon the military leader Usama. The great companion said, “Do not kill an old man, a woman, or a child. Do not injure date palms and do not cut down fruit trees. Do not slaughter any sheep or cows or camels except for food. You will encounter persons who spend their lives in monasteries (i.e., peaceful Christians). Leave them alone and do not molest them” (qtd. in The First Caliph, and based in the similar statements of the Prophet ﷺ himself, when he had lived).
Even within these limitations, personal anger is an invalid intention for lethal force as evidenced in the famous narration in which Ali, the fourth khalifah, Allah be pleased with him, was about to prevail in a fight when he tossed his sword aside in forfeit. Ali's opponent asked why he hadn't finished him off. Ali indicated he'd quit when when the man had spat in Ali's face. It had changed Ali's niyyah (intention) due to his anger at being spat upon. In Ali's heart, the sword fight shifted away from being about necessary defiance of tyranny and defense against extermination. His anger stemmed from his own, personal, motives. He couldn't kill a man for those reasons.
Anyone who behaves rashly and kills citizenry has violated the Shari’ah and is going against the way of Prophet Muhammad ﷺ.