I think they are the Shia Sunni and Kurds or possibly Sufi
Reform (Least Religious) Conservative (More Religious) Orthodox (Most Religious)
islam, chistianity, judaism
The 3 main religious groups are: -Christianity -Judaism (Jewish) -Islamic The previous answer is not correct. The religions listed above are the Abrahamic Religions and not the main religious groups of the world. There are literally hundreds of thousands of religious groups, and possibly thousands of "main" religious groups.
Allied Side: Coalition Military. Opposing side: Iraq Insugency, numerous other militarized groups oppsing the Coalition.
the three main groups are that you gey(:
The three main groups in science are chemistry,biology and physics.
Christianity and Islam
The main ethnic groups in Iraq are Arabs, Kurds, and Turkmen. Arabs are the majority and are predominantly located in central and southern Iraq. Kurds are the second-largest group and reside primarily in the northern regions. Turkmen, also known as Turcoman, are a smaller ethnic group mainly found in the north and have Turkic origins. Additionally, Iraq is home to several smaller ethnic communities, including Assyrians, Yazidis, and Chaldeans.
nincompoop
To narrow it down to three groups, it would be strings, winds, and percussion.
It has three main groups.
Roman catholics and church of England protestants.