is a non muslim wear a muslim religious dress

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

It is an obligation to endeavor to explain Tawheed (Oneness of Allaah) to non-Muslims and convince them of it and of shunning Shirk (associating partners to Allaah); this is what a Muslim should seek and endeavor to achieve.

As regards the dress, if Thimmis (non-Muslims living in a Muslim country) are in a country where there is a Muslim ruler who applies the Sharee‘ah, then he should oblige them to wear a dress by which they are to be distinguished from the Muslims, among which is the Zunnaar (a distinctive belt worn in the past by Christians); as stated by An-Nawawi in Al-Majmoo‘, ‘Ulaysh in his Fataawa, and Ibn Al-Qayyim in I‘laam Al-Muwaqqi‘een.

Shaafi‘i scholar Al-Maawardi said: “As for the difference between what Thimmis and Muslims  are to wear and ride, Thimmis are to be held liable for such differences as a condition under their pact with the Muslims so that they are distinguished and recognized and so they do not resemble Muslims and thus be able to evade the difference of rulings that pertain to each...”

Moreover, Ibn Qudaamah said in Al-Kaafi: “They must be distinguished from the Muslims in four things: their dress, their hair, what they ride, and their nicknames.”

As for the Muslim individual, he does not have a specific dress, but there are general conditions which he must observe in what he wears. For more benefit, please refer to Fatwa 88123.

Allaah Knows best.