A norm nowadays in our Muslim society is to keep company with mushrikeen and kuffaar.

Answer

The Qur'aan and the Sunnah are explicit in the prohibition of friendship and business partnership with non-Muslims. The Qur'aan explicitly and emphatically warns of taking non-Muslims as confidantes.

Associating and mingling with them on a social level constrains emulating them – acting like them, speaking like them, dressing like them and consuming doubtful and haraam food like them.

Foul language and interaction with the opposite sex are integral to the lifestyle of non-Muslims. Muslims who join the company of non-Muslims are also the weaker ones with grossly deficient Imaan and bereft of Islamic culture. Even their Imaan is compromised when they become integrated into non-Muslim lifestyle.

When Hadhrat Umar (radhiyallahu anhu) became the Khalifah, he enacted a law to compel Muslims and non-Muslims to dress differently so that they could be recognized from their apparel and outward appearance. When Jibraeel (alayhis salaam) would visit Rasulullah (sallallahu alayhi wasallam) in human form, he would make musaafahah (i.e. shake hands). On one occasion, he refused to shake Rasulullah's hands. When asked for the reason, Jibraeel (alayhis salaam) responded that yesterday Rasulullah (sallallahu alayhi wasallam) had shook hands with a Mushrik.

In short, all these acts of mingling and associating on a social and fraternal level with non-Muslims are not permissible.

Abstention from socializing and fraternizing is not permission for displaying enmity and bad behaviour towards non-Muslims. It is incumbent to display good moral character towards them and if necessary to assist them. But assimilation and integration are not permissible. It is Waajib for the Muslim to maintain his/her Islamic identity.