Here's the difference
Wishing & Imitating

For one it’s okay and for other is shirk however the line comes in between

Wishing is Makrooh-E-Tehreemi(MET)
Even if one Imitates without respecting and honouring their celebration, one will not become a Kafir. However this will be MET

What is Makrooh-e-Tahrimi ?
Makrooh-e-Tahrimi is an impermissible act in Deen. It's status is close to status of a haraam act. If one carries out a makrooh-e-tahrimi act, one will be sinful. The consequence of continuously carrying out a makrooh-e-tahrimi act could be disastrous
A non-muslim girl told me yesterday I wish you in Eid but you don't do in our Diwali, Xmas.
Wishing & Imitating is allowed in your religion but it is forbidden in mine

A non muslim comes to masjid by his choice because they don't have any rules but we couldn't go to mandir as
per our restriction

Islam comes with set of rules and boundries. To establish relation is okay but upto some extent.

At last,
"For you is your religion and for me is mine"
Qur'an 109:6
After everything what if a muslim does that sin. S/He wished or s/he participates does she becomes kafir?
See it completely depends on "Niyat"(intention) If one believes there religion is true then the individual is Kafir or the deed is shirk. If not then it is sin goes under MET
Islam is a religion of mercy, tolerance and moderation. It teaches its followers to be moderate in all fields and walks of life: in aspects of worship, in dealing with others, and in interaction with members of other faiths. Being extreme in one way or another would entail going
against the pristine teachings of Allah Most High and His beloved Messenger (Allah bless him & give him peace).

If one was to look at the various texts of the Qur’an and Sunnah with regards to interaction and communication with non-Muslims, this aspect (of moderation) would
become even more manifest and clear. On one hand, Islam commands us not to love and befriend non-Muslims, whilst many other texts and the practices of the Messenger of Allah (Allah bless him & give him peace) and his companions (Allah be pleased with them) indicate that one
should treat non-Muslims in the most respectful and amicable of ways.

Unfortunately, those who do not have a deep understanding of Islam seem to think there is a contradiction in the teachings of Islam with regards to how one’s behaviour should be towards non-Muslims.
They see the various texts of the Qur’an and Sunnah admonishing those who have close relationship and friendship with non-Muslims, whilst other texts seem to indicate that having good ties with non-Muslims is permitted and encouraged. Similarly, some non-Muslims point fingers at
Islam and its followers that Islam teaches hatred, violence and revulsion against non-Muslims.

However, with the above explanation, it becomes clear that both these understandings are way off the mark. There is no contradiction in the teachings of Islam; neither does Islam teach
its followers to have hatred for fellow human beings even if they be from another faith. The reality is that Islam teaches moderation. It allows Muslims to have a good relationship with non-Muslims but to a certain limit. This becomes clearer by looking at the various texts of
the Qur’an and the practices of the Messenger of Allah (Allah bless him & give him peace) and his companions.

There are many verses of the Qur’an that prohibit one from having close and intimate relationship with non-Muslims, for example:
1) Allah Most High says in the Qur’an:

“The believers must not take the disbelievers as friends instead of the believers. And whoever does that has no relation with Allah whatsoever, unless you [do so] as a protective measure [in order to] save yourself from them.”
(Surah Aal Imran, V: 28)

Imam Abu Bakr al-Jassas (Allah have mercy on him) states in the explanation of this verse:

“The statement of Allah “unless you [do so] as a protective measure [in order to] save yourself from them” “” means, if you fear for your life or limbs of your
body from them, then you may save yourselves from them by expressing friendship with disbelievers without it being from the heart…This is the opinion of the majority of scholars.” (Ahkam al-Qur’an, 2/289)

2) Allah Most High says:

“O you who believe! Take not my enemies and
yours as friends offering them [your] love…” (Surah al-Mumtahina, V: 1)

Imam Abu Bakr al-Jassas (Allah have mercy on him) states that this verse was revealed regarding the Companion Hatib ibn Abi Balta’a (Allah be pleased with him) who wrote to the non-believers of Quraysh
giving them guidelines (with regards to their safety and other such matters). He did so, as he feared for his wealth and children that he had left behind in Makka…” (Ahkam al-Qur’an, 5/325)
3) And “O you who believe, do not take the Jews and the Christians for intimate friends. They are friends to each other. Whoever takes them as intimate friends is one of them.” (Surah al-Ma’idah, V: 51)
Imam Ibn Kathir (Allah have mercy on him) states in the commentary of this verse:

“Allah Most High prohibits (in this verse) his believing servants from having close friendship and intimacy with the Jews and Christians – those who are enemies of Islam and its people…”
(Tasir Ibn Kathir, 2/94)

4) And:

“You shall not find any people who believe in Allah and the Last Day, loving those who resist Allah and His Messenger, even though they were their fathers or their sons, or their brothers, or their kindred.” (Surah al-Mujadala, V: 22)
The above few verses of the Qur’an indicate that it is unlawful to have close friendship and intimacy (muwalat) with non-Muslims, even if they were related to one. However, many other texts of the Qur’an and Sunnah, the action and practice of the Messenger of Allah (Allah bless
him & give him peace), his companion’s treatment of non-Muslims all indicate that one should treat non-Muslims with sympathy, generosity, compassion and concern.

1) Allah Most High says:

“Allah forbids you not, with regards to those who fight you not for (your) Faith nor drive
you out of your homes, from dealing kindly and justly with them: for Allah loves those who are just.” (Surah al-Mumtahina, V: 8)

2) And:

“O you who believe! Stand out firmly for Allah, as witnesses to fair dealing, and let not the hatred of others to you make you swerve to
wrong and depart from justice. Be just: that is next to piety: and fear Allah. For Allah is well-acquainted with all that you do.” (Surah al-Ma’idah, V: 8)

In the above two verses, Allah Most High commands us to treat non-Muslims justly and honorably.
The dislike of their beliefs should not prompt a Muslim to treat them unfairly.

The beloved Messenger of Allah (Allah bless him & give him peace), who was sent as a mercy for the whole of mankind, demonstrated such kindness, compassion, generosity and politeness towards
non-Muslims that it is difficult to find similar examples in history.

When Makka al-Mukarrama was in the grip of famine, he personally went out to help his enemies who had made him leave his home town. At the conquest of Makka, all his enemies came under his power and control,
yet he set them all free saying that not only are you being given amnesty today but rather you are also forgiven for what you have done in the past. When non-Muslim prisoners of war were presented before him, he treated them with such kindness and tenderness as one would treat
his own children. His enemies inflicted upon him all sorts of injuries and pain but he never raised his hand in revenge neither did he wish ill for them, rather he would pray for their guidance. A delegation from the tribe of Banu Thaqifa (who had yet not accepted Islam) came to
visit him, and was given the honour of staying in the Mosque of the Prophet, a place regarded by Muslims to be the most sacred of places. (See: Ma’arif al-Qur’an, 2/51)

There are many more such examples in the life of the Messenger of Allah (Allah bless him & give him peace).
The episode of Ta’if, the treaty of Hudaybiyya and many other such events quite categorically demonstrate the viewpoint of Islam with regards to treating and dealing with non-Muslims.

Likewise, the Companions (sahaba) of the Messenger of Allah (Allah bless him & give him peace)
also treated non-Muslims with tenderness and kindness. They gave them their just rights and did not oppress them in any way.

As such, the verses of the Qur’an that caution against friendship with non-Muslims are not referring to each and every type of friendship and
relationship. We see that Islam forbids its followers from being very intimate with non-Muslims, but at the same time, it does not prevent one from treating them in a cordial and generous manner.
Based on the above, classical Muslim scholars and jurists have categorized friendship with non-Muslims into four levels and stages:

1) Muwalat or Mawadda: This means to have close and intimate relationship and deep love and affection from one’s heart for a non-Muslim such that
it makes a Muslim unmindful of his faith. At times, it might even shape up as an impediment and hinder a believer from carrying out his/her religious duties – since ‘deep intimacy’ makes one blind and thus could result in undermining one’s religious duties.
This Mawadda is reserved only for Muslims; hence it is not permitted for a Muslim to have this type of friendship with non-Muslims. The verses of the Qur’an prohibiting Muslims from having intimate and close friendship with non-Muslims, especially the first verse of
Surah al-Mumtahina, is regarding this kind of relationship.

2) Mudarat: This means to express friendship and love only outwardly without having love for them and their beliefs internally. It is a mere outward expression of the first stage (muwalat), hence it entails being
pleasant, friendly, polite and kind towards non-Muslims. It involves expressing good manners, courtesy and good behavior towards fellow human beings.

This kind of relationship with non-Muslims is permitted, as it is reserved for all human beings, whether Muslim or non-Muslim.
This becomes even more important when the objective is to safeguard one’s self from potential harm, invite them towards Islam or when they are one’s guests. The verse of the Qur’an where Allah says “unless you [do so] as a protective measure [in order to] save yourself from them”
refers to this type of relationship. However, if one fears undermining his/her religious values, then this type of friendship will also not be permitted with non-Muslims.

3) Muwasat: This means to help, assist and benefit non-Muslims. It includes charitable help and support,
condolences and consolations, and removing harm, such as giving water to a thirsty non-Muslim or food to someone who is hungry.

This is also permitted with all types of non-Muslims except those who are directly at war with Muslims. The verse of the Qur’an where Allah Most High
says: “Allah forbids you not, with regards to those who fight you not for (your) Faith nor drive you out of your homes, from dealing kindly and justly with them: for Allah loves those who are just” refers to this kind of relationship with non-Muslims.

4) Mu’amalat: This means to
deal, transact and trade with non-Muslims. This is also permitted with all non-Muslims except when it is harmful to Islam and Muslims in general. (Culled from: Ahkam al-Qur’an, al-Fatawa al-Hindiyya, Ma’arif al-Qur’an, 2/50-51, Jawahir al-Fiqh, 179-193 and Ifadat
Ashrafiyya, P: 11)

It is clear with the above four levels that according to Islamic teachings, to take non–Muslims as friends and associates, in general, is permissible. It is perfectly acceptable to express outward friendship towards them, engage in business transactions and
dealings with them, be respectful, kind, polite, considerate, smile at them, help them if they need assistance, and generally exhibit good manners towards them and be socially good to them. In fact, this is not only permissible but encouraged.
However, what is discouraged and prohibited is to have an extremely deep and intimate connection and a “free and careless” type of association which leads to and causes grave religious harm.
Islam (and in fact every other faith) does not tolerate any compromise in contravening its basic beliefs and laws.

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