Muslim, and Hindu as well:

Sikander is one among the 10-lakh strong community of Cheetah-Kathat-Mehrat — spread over the four districts of Ajmer, Bhilwara, Pali and Rajsamand in Rajasthan — who are in a unique predicament over their religious identity. Descendants of the Chauhan rulers, the community took to Islam about 700 years ago, and adopted only the three practices of dafan, khatna and zabiha (burial, circumcision and eating halal) from the religion. The rest of their lifestyle — names, marriage rituals, dressing styles — continued to be the same as Hindus.

as an empirical matter this will be less common i suspect. in east java in the 1960s a large number of ’syncretistic’ muslims switched their affiliation to balinese hinduism because they did not identify with santri islam. similarly, those self-identified muslims who retain many “hindu” customs will be pressured to abandon them. globalization is a reality.