The following is excerpted from 'Answers to common questions to new Muslims' (Published 1993 by the Islamic Assembly of North America):
 

Mixing with non-Muslims Removes One' s Religious Pride and Jealousy
 
Question: I live in an area in which most of the residents are from our brethren Christians. We eat and drink with some of them. Is my prayer not valid and my living with them not allowed?

Answer: Before responding to the question, I would like to comment on something that I hope you said unintentionally. This is your statement, "Our brethren Christians". There is never any brotherhood between Muslims and Christians. Brotherhood must be based on faith. As Allah says: "Verily the believers are but a brotherhood" (al-Hujurat 49:10). If blood relationships come to an end because of differences in religion, how can brotherhood be confirmed for people of different religions and no blood relations? 

Allah says about Noah and his son: "[Noah said,] 'O my Lord, verily my son is of my family! And certainly your promise is true, and You are the Most Just Of the judges.' He [Allah] said, 'O Noah! Surely he is not of your family, his work is unrighteous"' (Hud 11 :45-46) There is never brotherhood between a believer and a disbeliever. In fact, it is obligatory upon the believer not to take a disbeliever as his close friend and ally. Allah says in the Quran, "O believers! Take not My enemies and your enemies as friends, showing affection towards them, while they have disbelieved in what has come to you of the Truth" (al-Mumtahana 60:1). 

Who are those enemies of Allah?  The enemies of Allah are the disbelievers. Allah says, "Whoever is an enemy to Allah,  His Angels, His Messengers, Gabriel and Michael, then verily,  Allah is an enemy to the disbelievers" (al-Baqara 2:98). Allah  also says, "O Believers! Take not the Jews and the Christians  as friends and helpers. They are but friends to one another.  And if any among you takes them as friends and allies, then  surely he is one of them. Verily, Allah does not guide the  wrongdoers" (al-Maida 5:51).  Therefore, it is not permissible for a Muslim to describe  any disbeliever as a brother - whatever type of disbeliever he is, be he Christian, Jew, Magian or atheist. Be aware, dear  brother, of making such a statement.

Now as for the response to your question, I state : You  should try to remain away from mixing with non-Muslims because mixing with them removes your religious zealousness  and pride from your heart and may lead you to having love  and compassion in your heart for them. Allah has stated, "You (O Muhammad) will not find any people who believe in Allah  and the Last Day making friendship with those who oppose Allah and His Messenger, even if they were their fathers, or their  sons, or their brothers, or their kin. For such He has written faith in their hearts and strengthened them with proofs from Himself And We will admit them to gardens through which  rivers flow, to dwell therein (forever). Allah is pleased with  them, and they with Him. They are the party of Allah, Verily, it is the party of Allah that will be the successful." (al-Mujadalah 58:22).
 

A Disbeliever is not a Muslim' s Brother
 
Question: I live with a Christian who calls me his brother and we are like brethren, we eat and drink together. Is this kind of deed permissible?

Answer: A disbeliever is not a Muslim's brother. Allah has said, "Verily the believers are but brethren" (al-Hujurat 49:10).  The Prophet (peace be upon him) also said, "A Muslim is a  brother to a Muslim". A disbeliever, whether he be Jew, Christian, Magian, Socialist or whatever, is not a brother to a Muslim. It is not allowed to take him as a companion and close  friend. However, if one eats with him sometime, without taking him as a companion, due to a general invitation or specific gathering, there is no harm in that. But to take him as a companion, close friend and dining associate, this is not allowed. Allah has cut off such ties of love, loyalty and friendship between Muslims and disbelievers. Allah says in His Noble Book,  "Indeed, there is an excellent example for you in Abraham and those with him, when they said to their people, 'Verily, we are free from you and whatever you worship besides Allah, we have rejected you, and there has started between us and you, hostility and hatred forever - until you believe in Allah alone'" (al-Mumtahana 60:4). 

Allah has also said, "You (O Muhammad) will not find any people who believe in Allah and the Last Day making friendship with those who oppose Allah and His Messenger, even if they were their fathers, or their sons, or their brothers, or their kin. For such He has written faith in their hearts and strengthened them with proofs from Himself  And We will admit them to gardens through which rivers flow,  to dwell therein (forever). Allah is pleased with them, and they with Him. They are the party of Allah. Verily, it is the party of  Allah that will be the successful" (al-Mujadalah 58:22) 

Therefore, it is obligatory upon a Muslim to be free of the  people of infidelity and to hate them for the sake of Allah. However, one must not harm them, hurt them or oppose them  without justice and rights to do so, as long as they are not fighting us. At the same time, though, one does not take them as comrades or brothers. If one coincidentally eats with them  at a general invitation or specific event, without companionship, loyalty or love for them, then there is no harm in that act. It is obligatory upon Muslims to deal with disbelievers in an Islamic fashion with proper behavior, as long as they are  not fighting the Muslims. One must fulfill one's trusts to them, must not deceive them, must not betray them or lie to them. If there is a discussion or debate between them, one must argue with them in the best manner and be just with them in the dispute. This is in obedience to Allah's command, "And argue not with the People of the Scriptures (Jews and Christians) unless it be in a way that is better, except with such of them as do wrong" (al-Ankabut 29 :46). 

It is sanctioned for the Muslim to invite them to the good, to advise them and to be patient with them at the same time being neighborly and polite with them. This is so because Allah has stated, "lnvite to the way of your Lord with wisdom (of the Quran) and fair preaching, and argue with them in a way that is better" (al-Nahl 6: 25). Allah has also said, "Speak good to people" (al-Baqara 2:83). The Prophet (peace be upon him) has also said, .'The one who guides to good will have the same reward as the one who does that good". Actually, there are numerous verses and hadith  with the same meaning.
 

The Ruling About Mixing with the Disbelievers
 
Question: What is the ruling concerning mixing with the disbelievers and being soft and gentle with them in hopes that they will embrace Islam?

Answer: There is no doubt that a Muslim is obliged to hate the enemies of Allah and be free of them. This was the way of the messengers and their followers. Allah says, "Indeed, there is an excellent example for you in Abraham and those with  him. when they said to their people, 'Verily, we are free from you and whatever you worship besides Allah, we have rejected you, and there has started between us and you, hostility and hatred forever - until you believe in Allah alone"' (al-Mumtahana 60 :4). Allah has also said, "You (O Muhammad) will not find any people who believe in Allah and the Last Day making friendship with those who oppose Allah and His Messenger, even if they were their fathers, or their sons, or their brothers, or their kin. For such He has written faith in their hearts and strengthened them with proofs from Himself " (al-Mujadalah 58:22). 

Based on these, a Muslim is not allowed to have love and compassion in his heart for the enemies of Allah who are in reality his own enemies. Allah has stated, "O believers! Take not My enemies and your enemies as friends, showing affection towards them, while they have disbelieved in what has come to you of the Truth". (al-Mumtahana 60: 1). But there is no harm for a Muslim treating them with kindness and gentleness in hopes that they become Muslim. This is a type of reconciling their hearts to Islam. However, if one despairs in their becoming Muslim, then one may treat them in the way that they may be treated. And this is dealt with in detail in the law books, in particular ibn al-Qayyim's Ahkam ahl al-Dhimmah.
 

The Ruling Concerning Having Love for the  Disbelievers
 
Question: What is the ruling concerning having love for the disbelievers and preferring them to the Muslims?

Answer: There is no doubt that the one who loves the disbelievers more than he loves the believers is committing a great sin. It is obligatory upon him to love the Muslims and to love for them what he loves for himself. If he loves the enemies of Allah more than he loves Muslims  this is very dangerous and forbidden. In fact, it is not even allowed to love them even  if one loves them less than he loves the Muslims. Allah has stated, "You (O Muhammad) will not find any people who believe in Allah and the Last Day making friendship with those who oppose Allah and His Messenger, even if they were their fathers, or their sons. or their brothers. or their kin. For such He has written faith in their hearts and strengthened them  with proofs from Himself And We will admit them to gardens through which rivers flow. to dwell therein (forever). Allah is pleased with them, and they with Him. They are the party of Allah. VeriIy. it is the party of Allah that will be the successful." (al-Mujadalah 58:22). 

Allah has also said, "O believers! Take not My enemies and your enemies as friends. showing affection towards them. while they have disbelieved in what has come to you of the Truth" (al-Mumtahana 60: ). Furthermore,  whoever praises them and prefers them over the Muslims in deeds and otherwise, then he has committed a sin and has not had proper thoughts about his brethren Muslims. And he has had good thoughts about those people who are not deserving of such thoughts. It is obligatory upon the believer to prefer Muslims over others in every aspect, in deeds and otherwise. If one finds shortcomings in Muslims. he must advise them. warn them and explained to them the wrong they are doing. Perhaps, Allah may guide them through his hands.'
 

Ruling Concerning Honoring a Disbeliever  by Giving Him Wine
 
Question: Is it allowed for a Muslim to honor his non-Muslim friends by giving them food or drink that is forbidden in Islam?

Answer. Islam is the religion of forgiveness, easiness and simplicity. At the same time, though. it is a religion of justice. Generosity is an Islamic character. However, if the person is a disbeliever, then the ruling concerning that generosity differs depending on the intention of the person himself and depending on what he offers as an act of kindness. The intent could be legally sanctioned. If he wants to make some contact with the person until he invites him to Islam and rescues him from disbelief then that is a noble intention. One of the principles of Islamic law is that the means has the same ruling as the goal. If the goal is obligatory, then the means become obligatory. If the goal is forbidden, then the means are also forbidden. If there was no legally sanctioned goal behind the generosity and the person would not be harmed by not being kind, then it is permissible for him not to be so. However, it is not allowed to do acts of generosity or kindness with things that Allah has forbidden. such as pork or alcohol. By giving such items, the person has disobeyed Allah and obeyed them. He has preferred their rights over that of Allah. A Muslim must stick to his religion. In a non-Muslim land, he must openly demonstrate his applying Islam in order to be a caller to Islam in both word and action.
 

The Ruling Concerning Business Transactions with the Disbelievers
 
Question: Is it valid to have business transactions or trading with the disbelievers while we are aware that they are disbelievers? And, in particular, when we are in need of what they manufacture?

Answer. Allah willing, there is no harm in using what the disbelievers manufacture if there is some need to do so, as is what is happening these days as items, products, appliances and so forth are imported from non-Muslim countries. This need makes us come into agreements with them concerning price, amount and quality and how the items will be received and paid for [All of this is allowed.]'
 

Ruling Concerning Greeting a Disbeliever
 
Question: How shall we respond to a disbeliever if he greets us?

Answer: It is confirmed that the Messenger of Allah (peace be upon him) said. ."Do not be the first to greet a Jew or Christian with peace. And if you come across them in the walkway, force them to the edges." Muslim recorded this in his Sahih. He (peace be upon him) also said, .'If the People of the Book greet you with peace. say, 'Wa alaikum (and unto you).'" This was recorded by al-Bukhari and Muslim. The People of the Book are the Jews and Christians. The ruling concerning the other disbelievers is the same as the ruling of the Jews and Christians in this matter since there is no evidence to show otherwise. In general, one does not first greet a disbeliever. However, if he starts the greeting, then one must respond by our statement, "And upon you", in accord with the order from the Messenger (peace be upon him). There is no prohibition to say after that, something like, "How are you? How are your children?" Some of the scholars, including ibn Taimiya, has said that this is permissible. This is especially acceptable if there is some Islamically sanctioned reason for that, such as hoping the person will become Muslim or making him susceptible to your calling him to Islam. Allah has stated, "Invite to the way of your Lord with wisdom (of the Quran) and fair preaching, and argue with them in a way that is better" (al-Nahl 16: 125). Allah has also said, ."And argue not with the People of the Scriptures (Jews and Christians) unless it be in a way that is better, except with such of them as do wrong" (al-Ankabut 29:46).'
 

The Ruling Concerning a Gift from the Ad-hiya to non-Muslim Neighbors
 
Question : Does the non-Muslim neighbor have a portion of the adhiya or not?

Response: It is permissible for a Muslim to assist his non-Muslim neighbor by giving him some meat from his sacrificed animal. He may give it to them in order to soften their hearts and to fulfill the rights that neighbors have upon one another. This is so because there is no evidence prohibiting such an act and due to the generality of Allah's statement in the Quran, "Allah forbids you not to deal justly and kindly with those who fought not against you on account of religion and drove you not out from your homes. Verily, Allah loves those who deal with equity". (al-Mumtahanah 60:8). In fact, the Permanent Committee gave a ruling on this question. This is the text of their response:

    Yes. it is allowed for us to give food to the disbelievers living under the Islamic state and wayfarers from the meat of the sacrificed animal. It is allowed to give to them on the basis of  their poverty, blood relation, being a neighbor or to soften their hearts. The ritual act is the actual act of slaughtering which is an act of worship and getting closer to Allah. As for the meat of said animal, it is best for the person to consume one third of it himself and to give one-third of it as a gift to his relatives and neighbors and friends, and to give another third away in charity to the poor. If the shares are slightly off from those portions. there is no harm as the matter is a wide one and not strict. However, one should not give such meat to a harbi (someone who is fighting against the Muslim state) be cause in their case, the obligation is to suppress and weaken them and not assist or strengthen them with charity. In fact,   that is the ruling with respect to all forms of voluntary charity, based on the generality of the verse in the Quran, "Allah forbids you not to deal justly and kindly with those who fought not against you on account of religion and drove you not out from your homes. Verily, Allah loves those who deal with equity" (al-Mumtahanah 60 :8). Furthermore, the Prophet (peace be upon him) ordered Asma bint Abu Bakr (may Allah be pleased with her) to help her mother out with money although she was a polytheist. 
 

Giving Voluntary Charity to non-Muslims:
 
Question: Is it permissible to give charity to non-Muslims?

Response: It is not permissible to give zakat to the non-Muslims. Furthermore, it is disliked to give voluntary charity to the non-Muslims because, in so doing, you are supporting them in their disbelief Allah says in the Quran, "But do not help one another in sin and transgression" (al-Maidah 5:2). However, if you hope for someone to be Muslim. then there is  no harm in giving him some charity in the hope that it might  encourage him to become Muslim. If you fear that someone is about to die, it is permissible to save him from death in order to let him know about the beauty of lslam.
 

Observing or Recognizing the Holidays of the Jews and Christians is not Allowed
 
Question: some Muslims recognize the holidays of the Jews and Christians. When a Jewish or Christian holiday comes, they close the Islamic schools because of those holidays. However, on Muslim holidays, they do not close the schools. They argue that by observing the Christian and Jewish holidays, those people might be led to Islam. We would like you to clarify this matter.

Answer: First, the practice is to publicly display the signs of Islam among Muslims and to avoid anything that goes against the guidance of the Messenger (peace be upon him). It is confirmed that he said, ."You should follow my way (sunnah) and the way of the rightly guided successors..."

              Second, it is not allowed for Muslims to participate with  the disbelievers in their holidays or to show joy and happiness for such occasions. Similarly, one cannot cancel work for such an occasion. This is true whether the occasion be a religious or secular holiday. To do so would be a forbidden imitation of the  enemies of Allah. It is confirmed that the Messenger of Allah (peace be upon him) said, "Whoever imitates a people is one of  them."

              We advise you to refer to the book lqtidha al-Sirat al-Mustaqeem by Shaikh al-lslam ibn Taimiya as it is very beneficial  concerning this matter.