You're addressing holiday cards, or planning the office party, and you'd rather ask the internet than make it weird. Fair. The answer is that Muslims differ: recognized scholarly positions run from complete nonparticipation to permitted greetings and family meals, and individuals follow their own convictions across that range. The positions sit below, side by side. What's safe for you to say and do is the easy part.
Every position below is held by a named institution (Egypt's Dar al-Ifta, the Fiqh Council of North America, IslamQA, MuslimSG, IMAM-US, and scholars at SeekersGuidance among them), and the institutions disagree. Qadir issues no rulings.
Muslim scholarly institutions genuinely disagree here, so Muslims land in different places by conviction, not confusion. Some authorities (like the site IslamQA) hold that participating in Christmas festivities isn't permissible at all. Others (Egypt's Dar al-Ifta among the most prominent) permit sharing family meals and good wishes so long as no religious rites contrary to Islam are involved. Your one Muslim friend who sends Christmas cards and your other one who quietly sits it out are both being consistent.
Muslims deeply revere Jesus: 'every Muslim believes that Jesus is a human and a prophet,' as Dar al-Ifta puts it. But Islamic theology differs from Christian doctrine on who Jesus is, and Islam has its own two annual holidays, the two Eids. So Christmas sits in genuinely debated territory: honored figure, another tradition's feast. The debate is about participation in the celebration, never about respect for Jesus, which is a given.
Multiple named institutions permit Muslims to give and receive holiday greetings: Dar al-Ifta, Singapore's MuslimSG (which calls the greeting-equals-shirk view 'incorrect'), the Office of Ayatollah Sistani ('There is no harm in greeting them on their occasions'), and IMAM-US. IslamQA prohibits it: 'It is also not permissible to offer congratulations.' Gifts split the same way: Dar al-Ifta counts gift-giving among acts of goodness, FCNA sees nothing wrong in accepting a gift from Christian family or friends, AMJA permits accepting a permissible gift but says a Muslim must refrain from giving gifts on those holidays, and IslamQA prohibits Christmas-specific gifts. So if you wish a Muslim coworker 'Merry Christmas,' you may get it back, or a 'thank you' with a smile, which FCNA explicitly recommends as the response from those who don't return the greeting. Read neither as a verdict on you.
Each position has a holder. IslamQA's office ruling prohibits participation, gifts, and decorations. The Fiqh Council of North America says it is better not to attend absent a strong reason, but permits necessity-based attendance, maintaining composure and disapproving prohibited conduct. Dar al-Ifta allows social sharing bounded by avoiding religious rites that contradict Islam. And IMAM-US, in the Sistani-linked North American Shia framework, says sitting at a table where alcohol is served is prohibited 'based on obligatory precaution.' The practical read-across: disclose what the event involves, make food and alcohol arrangements transparent, and treat nobody's attendance as a loyalty test in either direction.
The pattern repeats, with names attached. Birthdays: Dar al-Ifta finds 'no legal impediment,' the Assembly of Muslim Jurists of America (AMJA) cautions that they follow an imported culture, and IslamQA calls them an innovation in religion. Halloween: Dar al-Ifta permits creed-compatible social participation, while Shaykh Dr Muhammad Abu Bakr Badhib, writing for SeekersGuidance, rules the costumes and activities not permissible. Thanksgiving: SeekersGuidance scholars permit it as cultural or national (including a family turkey dinner with halal food and no alcohol), AMJA cautiously permits family gatherings that simply use the vacation time, and IslamQA's strict festival reasoning rejects participation. If you're inviting a Muslim friend to any of these, offer warmly, say what the event involves, and make declining easy.
The two Eids (al-Fitr after Ramadan and al-Adha in the Hajj season) are Islam's own annual holidays, full of food, family visits, gifts, and children's activities. ING recommends 'Eid Mubarak': its founder Maha Elgenaidi says a simple 'Eid Mubarak' ('Blessed Eid') goes a long way. 'Happy Eid' is the endorsed English alternative. Wishing a Muslim colleague well on their own holidays is a recommendation the sources themselves make.
Some participate in cultural and family ways; others abstain, both follow recognized scholarly positions, institutions genuinely disagree, from rulings against participation to Egypt's Dar al-Ifta permitting family meals and good wishes so long as no contrary religious rites are involved. Individual practice varies accordingly; there is no single Muslim answer.
You can offer it warmly, the scholarly debate concerns whether Muslims offer the greeting, not how you address them, and the low-pressure move is simply to greet kindly and expect nothing specific back. Whether Muslims say it back is where scholars differ: several major institutions permit holiday greetings, stricter ones don't. If your greeting is met with 'thank you' instead of an echo, that's the graceful response one North American fiqh body itself recommends, not a snub.
It varies by conviction: Egypt's Dar al-Ifta finds no legal impediment to birthday celebrations, AMJA cautions that they follow an imported culture, and IslamQA considers them a religious innovation to avoid, so individual families land differently. Invite Muslim classmates or coworkers warmly, say what the party involves, and make declining easy.
Positions differ by name: scholars at SeekersGuidance permit Thanksgiving as cultural or national, including a family dinner with halal food and no alcohol, AMJA cautiously permits family gatherings that simply use the vacation time, and IslamQA's strict reasoning rejects recurring non-Islamic festivals. As ever, individual practice follows conviction.
Anything genuinely warm works: 'Merry Christmas' is acceptable to offer, and 'enjoy the break,' 'have a peaceful holiday,' or 'wishing you and your family well' are inclusive alternatives that don't put anyone's religious position on the spot. And their own holidays come with a recommended greeting: 'Eid Mubarak,' twice a year.
Offer it warmly and make declining easy, named authorities permit attending family and social gatherings, and others prohibit it, so the invitation should carry no pressure either way. Disclose the food and alcohol arrangements up front: Dar al-Ifta's family-meal guidance says to avoid pork and alcohol, and IMAM-US restricts sitting at a table where alcohol is served, so an alcohol-free meal or table is the accommodating offer. Take a decline gracefully, for some Muslims declining is itself the faithful choice.
A colleague's choice in either direction is a religious position, not a personality verdict: the strict view isn't hostility and the permissive view isn't assimilation, and institutional Muslim guidance says exactly that. When in doubt, warmth plus an easy out covers every case on this page.