Church, or culture.
denomination
religion
sect
order
cult
diocese
stake
parish
Another word for religious group could be "faith community" or "religious organization."
A group of religious people is often referred to as a congregation, parish, assembly, or community.
congregation
another word for large group is clan.
It is another word for 'cult' meaning something that can be regarded as fashionable by a particular group. The word also refers to a particular system of religious worship
'Dogma' is religious doctrine.
Friends
choir or orchestra is another word for music group
Words that refer to religious groups include religions, faiths, denominations, congregations, churches, branches, sects, factions, orders, and cults.
A sect is defined as a subdivision of a larger religious group, so the answer is yes.
Another word for gather or collect is... handle or group together.
The word is genocide.