Did Muhammad Forbid Privacy to Non-Muslims?
The Quran declares:
O ye who believe! Enter not houses other than your own until you have asked leave and saluted the inmates thereof. That is better for you, that you may be heedful. And if you find no one therein, do not enter them until you are given permission. And if it be said to you, ‘Go back’ then go back; that is purer for you. And God knows well what you do. 
The Qur’an forbids entering any home of another person, inhabited or uninhabited, without the owner’s permission, and commands people to retreat immediately when they are told to retreat from the home in question—all in the name of protecting a person’s privacy. The Qur’an makes no exception for “non-Muslim” homes, but specifically commands Muslims to, “enter not houses other than your own until you have asked leave.” In fact, a saying of Prophet Muhammad’s details how important privacy is in Islam:
A man peeped through a hole in the door of God’s Apostle’s house, and at that time, God’s Apostle had a Midri (an iron comb or bar) with which he was rubbing his head. So when God’s Apostle saw him, he said (to him), “If I had been sure that you were looking at me (through the door), I would have poked your eye with this (sharp iron bar).” God’s Apostle added, “The asking for permission to enter has been enjoined so that one may not look unlawfully (at what there is in the house without the permission of its people).” 
The indignation of the Prophet over the crime of the violation of one’s privacy is quite apparent from this incident.
Some might allege that this is a cruel punishment. On the contrary, this saying of the Prophet further strengthens Islam’s ardent protection of an individual’s privacy, particularly for women and minors—two classes that are most victim to sexual abuse. First, consider the ease with which a person can simply not take the unauthorized liberty of peering into another’s home without permission. Contrast that with the massive potential and actual threats that exist for those who are victim to such voyeurism. Based on the ease of compliance and the potentially devastating harm to a victim of privacy violations, an active deterrent is necessary to ensure privacy—for all people of all faiths—remains protected.
Next, critics claim the Qur’an 4:90, “if they desert you, seize them and put them to death wherever you find them,” refers to apostates. The reader will see shortly that nothing in this verse references apostates. Rather, it refers to hypocrites who first signed a peace treaty with the Muslims, and then violated that treaty. Critics cite only part of a verse to argue some asinine point—this is one such example. The verse is presented below, in proper context. It is easy to see how emphatically this verse promotes justice.
What has happened to you that you are divided into two parties regarding the hypocrites? And Allah has overthrown them because of what they earned. Desire ye to guide him whom Allah has caused to perish? And for him whom Allah causes to perish thou shalt not find a way. (4:89)
They wish that you should disbelieve as they have disbelieved, so that you may become all alike. Take not, therefore, friends from among them, until they emigrate in the way of Allah. And if they turn away, then seize them and kill them wherever you find them; and take no friend nor helper from among them; (4:90)
Except those who are connected with a people between whom and you there is a pact, or those who come to you, while their hearts shrink from fighting you or fighting their own people. And if Allah had so pleased, He would have given them power over you, then they would have surely fought you. So, if they keep aloof from you and fight you not, and make you an offer of peace, then remember that Allah has allowed you no way of aggression against them. (4:91)
Examining 4:90 in its proper context, it becomes difficult to understand what critics finds objectionable. In 4:89, God admonishes Muslims not to trust hypocrites, because they are, well, hypocrites.
Thus, Verse 4:90 has little to do with privacy—which is protected—and instead further admonishes Muslims not to befriend hypocrites because they may deceive Muslims at any moment. Due to the constraints of war, it prescribes capital punishment for treason—a concept explained earlier. Finally, 4:91 specifically qualifies the guidance provided in the previous two verses to forbid Muslims from fighting three groups of people: “Those who are connected with a people between whom and you there is a pact, or those who come to you, while their hearts shrink from fighting you or fighting their own people.”
Thus, Muslims are forbidden from fighting those with whom the Muslims have an established mutual relationship, those with whom a pact has been signed, and those who shy away from fighting. Commenting on this principle, Prophet Muhammad declared, “Whoever killed a person protected by a treaty shall not smell the fragrance of Paradise though its fragrance can be found at a distance of forty years (of traveling).” 
Likewise, 4:92 further clarifies, “if they do not keep aloof from you nor offer you peace nor restrain their hands, then seize them and kill them.” Thus, Muslims may only fight those who fight them first, and are absolutely forbidden from any aggression against those who do not fight Muslims, or make an offer of peace to Muslims.
Notice, the Qur’an makes no conditions on that peace offering other than a cease of fighting. Non-Muslims need not “submit” to Islamic authority, or convert to Islam, or relinquish their sovereignty. They need to only, “keep aloof, not fight, or make an offer of peace.”
Therefore, critics not only deceptively and incorrectly claim that 4:90 refers to apostates—indeed this verse has nothing to do with apostates—but they also altogether miss this just Qur’anic guidance to promote peace.
 Qur’an 24:28-29.
 Bukhari, Vol. 9, Book 83, #38.
 Bukhari, Vol. 9, Book 83, #49.