I know that a Muslim is the brother of his fellow Muslim and the enemy of the disbeliever. But if a Muslim seems to have a bad attitude and mistreats people, and a disbeliever is the opposite of that, the Muslim is more entitled to be spoken of well and treated well in all circumstances.
Allah, may He be exalted, and His Messenger (blessings and peace of Allah be upon him) have enjoined taking the believers as friends and opposing the disbelievers in many texts in the Book of Allah, may He be glorified and exalted, and the Sunnah of His Messenger (blessings and peace of Allah be upon him), let alone the words of the scholars and their unanimous agreement on that. Part of their ‘aqeedah (belief) is taking the believers as friends and opposing the disbelievers.
Allah, may He be exalted, says (interpretation of the meaning):
“O you who believe! Take not the Jews and the Christians as Awliya’ (friends, protectors, helpers, etc.), they are but Awliya’ to one another. And if any amongst you takes them as Awliya’, then surely he is one of them. Verily, Allah guides not those people who are the Zaalimoon (polytheists and wrongdoers and unjust)”
“Verily, your Wali (Protector or Helper) is Allah, His Messenger, and the believers, - those who perform As-Salat (Iqaamat-as-Salaah), and give Zakaah, and they bow down (submit themselves with obedience to Allah in prayer).
And whosoever takes Allah, His Messenger, and those who have believed, as Protectors, then the party of Allah will be the victorious.
O you who believe! Take not for Awliya’ (protectors and helpers) those who take your religion for a mockery and fun from among those who received the Scripture (Jews and Christians) before you, nor from among the disbelievers; and fear Allah if you indeed are true believers”
Shaykh Ibn Baaz (may Allah have mercy on him) said:
The Qur’an calls us to take the believers as friends and to oppose the disbelievers wherever they are and however they are.
End quote from Majmoo‘ Fataawa Ibn Baaz, 1/297
Allah, may He be exalted, says (interpretation of the meaning):
“O you who believe! Whoever from among you turns back from his religion (Islam), Allah will bring a people whom He will love and they will love Him; humble towards the believers, stern towards the disbelievers, fighting in the Way of Allah, and never afraid of the blame of the blamers. That is the Grace of Allah which He bestows on whom He wills. And Allah is All-Sufficient for His creatures needs, All-Knower”
Shaykh as-Sa‘di (may Allah have mercy on him) said:
The (believers) are very humble when dealing with other believers, meaning that they love them, are sincere, soft, gentle, compassionate, merciful and easygoing towards them. But the way they should behave towards those who disbelieve in Allah and reject His revelations and His Messengers, is to be stern towards them. The believers are all united in opposing them and they strive hard in every way to prevail over them. Allah, may He be exalted, says (interpretation of the meaning): “severe against disbelievers, and merciful among themselves” [al-Fath 48:27]. Sternness towards the enemies of Allah is something that brings a person closer to Him, as he is aware of the wrath of Allah towards them. However, this sternness should not prevent us calling them to Islam in a gentle way. In both cases, that serves their best interests and they will benefit from it.
End quote from Tafseer as-Sa‘di, p. 235
Muslim (2564) narrated that Abu Hurayrah said: The Messenger of Allah (blessings and peace of Allah be upon him) said: “Do not envy one another, do not artificially inflate prices, do not hate one another, do not turn away from one another, do not undercut one another. Be, O slaves of Allaah, brothers. The Muslim is the brother of his fellow-Muslim. He does not wrong him, let him down or despise him. Piety (taqwa) is here” – and he pointed to his chest three times. “It is sufficient evil for a man to despise his Muslim brother. The whole of a Muslim is sacred to another Muslim, his blood, his wealth and his honour.”
Al-Bukhaari (6011) and Muslim (2586) narrated that an-Nu ‘maan ibn Basheer said: The Messenger of Allah (blessings and peace of Allah be upon) said: “The likeness of the believers in their mutual love, mercy and compassion is that of the body; when one part of it is in pain, the rest of the body joins it in restlessness and fever.”
What the Muslim must do is show care towards his Muslim brother, help him, meet his needs and conceal his mistakes. If he makes a mistake or commits a sin, he should offer him sincere advice, enjoin him to do what is good and forbid him to do what is evil, and he should not leave him to his shaytaan or his nafs (self) that is inclined towards evil. If he commits a sin, major or minor, he should not disavow him or fail to show him the friendship and care that are his Islamic duty; rather he should disavow his wrongdoing, sin and enmity, whilst maintaining the basic principle of friendship and love because of the faith he has. If he gives up his sin and mistake, he should restore the ties of friendship and support, according to the situation.
With regard to the disbeliever, a Muslim has nothing to do with him because of his false religion and his being far away from the straight path of Allah. What comparison can there be between him and a believer, even if the latter falls short and is negligent?
With regard to speaking ill of his Muslim brother and putting him down in front of a disbeliever, whether he is of the people of the Book or otherwise, this is bad manners and is often indicative of a problem with one’s own ‘aqeedah. Many Muslims are enchanted by non-Muslims, because of what they appear outwardly to be, then if they see from another Muslim something that they dislike, they criticize him for his shortcomings and think that an non-Muslim is better than him.
But what is enjoined is for the Muslims to conceal one another’s faults, so how can one Muslim strive to expose another in front of the enemies of the Muslims, whether they are the people of the Book or otherwise? How can he give the enemies the opportunity to rejoice in the misfortunes of his fellow believer, or show them his faults and shortcomings? Rather Imam an-Nawawi (may Allah have mercy on him) said:
If a teacher says to the children, “The Jews are much better than the Muslims, because they give their children’s teacher his rights,” he has become a disbeliever!
End quote from Rawdat at-Taalibeen, 10/69
In fact this is the expected outcome of mentioning the bad deeds and faults of the Muslims in front of the enemies of Allah among the disbelievers. It ends up with the one who says that preferring the disbelievers over the Muslims, especially when he starts to compare them; what usually happens is that he reduces all characteristics to one, which he exaggerates to the exclusion of others and bases his judgement of people on that one characteristic.
The wise person should beware of helping (an enemy) against his brother or being a fitnah to the disbelievers by mentioning the faults of the Muslims in front of them, because by doing so he is barring them from the religion of Allah and turning them away from it.
And Allah knows best.