You must observe the Islamic State’s idea of morality, or they will kill you, which they consider to be a moral act.
The Islamic State statement quotes the Qur’an: “O you who believe! Take not the Jews and the Christians as Auliya’ (friends, protectors, helpers), they are but Auliya’ of each other. And if any amongst you takes them (as Auliya’), then surely he is one of them. Verily, Allah guides not those people who are the Zalimun (polytheists and wrong-doers and unjust)” (5:51)
Not that this has anything to do with Islam!
“Celebrating New Years amounts to practising idolatry says Islamic State,” by Vicky Nanjappa, OneIndia.com, January 1, 2017:
To celebrate New Year is practising idolatry, the Islamic State has said.
While warning Muslims against celebrating New Years the IS has said that it amounts to practising idolatry with the infidels.
In a statement released on pro IS English channels, the IS says, “to celebrate New Year’s Eve with the kuffar is to embrace their idolatry and paganism and to shun the rulings of our Lord.”
Allah says: “O you who believe! Take not the Jews and the Christians as Auliya’ (friends, protectors, helpers), they are but Auliya’ of each other. And if any amongst you takes them (as Auliya’), then surely he is one of them. Verily, Allah guides not those people who are the Zalimun (polytheists and wrong-doers and unjust)” (Al-Maidah 51). There is nothing to celebrate. The Gregorian calendar is rooted in kufr and blatantly ignores the lunar calendar and that introduced to follow the Hijrah of our honorable Prophet (SAWS). We also do not celebrate the start of a new year. Rather, we consider sacred the month of sacrifice and the ‘Eids, which are also times to consider our Muslim brothers and ourselves.If a Muslim finds himself amid such a celebration, the kuffar commit all kinds of sin – imbibing of alcohol, fornication, and debauchery – that must be avoided.