Answer:
(Fatwa: 50/48=B/1429)
Wishing ?merry Christmas? to Christians on 25 December is not right. Likewise, congratulating people of other religions on their festivals is not correct. Yes, one can express his wishes in good words like praying for peace and tranquillity or for security of the country or mutual unity and integrity.
It is also not proved to wish someone with Happy New Year on 1 January.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband
