None of the mainstream Christian denominations allow polygamy, especially in countries where it is illegal. There are several offshoot cults and churches which allow polygamy, but these are usually individual small churches (<1000 people) that cannot be considered denominations. There are some individuals, religious and not religious, who practice polygamy individually as well.
Some small groups within Islam, Christianity, and Hinduism allow or even advocate polygamy. In the United States, most religious polygamists belong to small Fundamentalist Christian sects, and many others are not religious or are independent of a religious group.
Several religious groups believe in or allow polygamy, including Muslims, some Hindus, and some Christians. Anciently (in Biblical times) Jews commonly practiced polygamy as well.
Islam is probably the largest religious group in the US that practices polygamy, although most Muslims are not polygamist.
The U.S. Constitution does not restrict the practice of polygamy. However, it does not explicitly or implicitly protect that right, which allows state and national legislatures to restrict it.--Polygamy is not mentioned in the constitution or in any of its amendments; the only prominent sect in the US that practiced polygamy (the Latter Day Saints) was established decades after the constitution was ratified. Polygamy is, however, against federal law.
Christian men do not have many wives and do not believe in polygamy. Only a small sect of Mormans engages in polygamy.
Shakers are a nearly extinct religious sect.
The current United States law against polygamy trumps religious freedom. It states that religious belief or practice cannot be used as a defense in polygamy cases.
A sect is defined as a subdivision of a larger religious group, so the answer is yes.
The Quakers
A sect is a group with distinctive religious, political or philosophical beliefs.
Henry Bitakaramire has written: 'Traditional and Christian marriage' -- subject(s): Christianity, Marriage, Marriage customs and rites, Polygamy, Religious aspects, Religious aspects of Marriage, Religious aspects of Polygamy
A religious group can be called a sect. A religious group can also be called a congregation when all attend the same church. A religious group might have more than one sect, or group of individuals, like the Amish.
The Jews.