How many main sects are in Christianity? I know that "main" can be interpreted differently, but I want a reasonable number so I get the idea.

Sect has a negative connotation -- often meaning cult. A more appropriate name for the different Christian beliefs is "denominations."

http://www.religionfacts.com/christianity/denominations.htm

Oh, okay. My teacher told me that those denominations are called sects, but I had no idea of its negative connotation.

To determine the number of main sects in Christianity, we can consider the major branches or denominations within the religion. It's important to note that interpretations may vary and some sources may cite different numbers, as there is no universally agreed-upon count. However, a reasonable number is approximately six major sects or branches of Christianity:

1. Catholicism: The largest sect of Christianity with a hierarchical structure headed by the Pope in Rome.

2. Protestantism: This category covers a wide range of denominations that originated from the Protestant Reformation, such as Lutheranism, Calvinism, Anglicanism, Methodism, and Baptist traditions.

3. Eastern Orthodoxy: Comprising multiple autocephalous churches, it includes the Greek Orthodox, Russian Orthodox, and others.

4. Oriental Orthodoxy: This branch encompasses the Coptic Orthodox Church, Armenian Apostolic Church, Ethiopian Orthodox Tewahedo Church, and others.

5. Assyrian Church of the East: Also known as Nestorianism, it is primarily practiced by the Assyrians in the Middle East and South India.

6. Restorationism: This category includes denominations that sought to "restore" the original teachings and practices of early Christianity. Examples include the Church of Jesus Christ of Latter-day Saints (Mormons), Jehovah's Witnesses, and Christian Science.

It's worth mentioning that within these major sects, there may be further divisions and subgroups with varying beliefs and practices.