How many religions is there in the world?

Enough to give war its definition.

There is a huge number of different religious groups (actually uncountable), but they are mostly organised inside a few major religions.


"Major Religions of the World
Ranked by Number of Adherents

(Sizes shown are approximate estimates, and are here mainly for the purpose of ordering the groups, not providing a definitive number. This list is sociological/statistical in perspective.)
Christianity: 2.1 billion
Islam: 1.5 billion
Secular/Nonreligious/Agnostic/Atheist: 1.1 billion
Hinduism: 900 million
Chinese traditional religion: 394 million
Buddhism: 376 million
primal-indigenous: 300 million
African Traditional & Diasporic: 100 million
Sikhism: 23 million
Juche: 19 million
Spiritism: 15 million
Judaism: 14 million
Baha'i: 7 million
Jainism: 4.2 million
Shinto: 4 million
Cao Dai: 4 million
Zoroastrianism: 2.6 million
Tenrikyo: 2 million
Neo-Paganism: 1 million
Unitarian-Universalism: 800 thousand
Rastafarianism: 600 thousand
Scientology: 500 thousand"
Source aud further information:
http://www.adherents.com/Religions_By_Adherents.html

Further information:
http://en.wikipedia.org/wiki/Religions_of_the_world
http://www.religion-cults.com/
http://www.religioustolerance.org/worldrel.htm

In this article, there are links to the divisions of the major religions:
http://en.wikipedia.org/wiki/Denominationalism

For instance, for the Christian religion:
http://en.wikipedia.org/wiki/List_of_Christian_denominations

Too many.

Over 9000.

If you look at societies throughout history, every one has had some type of religion. The Native Americans, ancient Egyptians, ancient Greeks and Romans, Hebrews, Muslims, Voo Doo, etc. There are a number of things you will find in common with all of them. They have a God or Gods or some higher level being that has power over them, their religion lays the groundwork for the moral structure of their society (i.e. 10 commandments for Christians), it is used to explain things that people don't understand (Hercules took the sun across the sky, God created the earth, etc.) and all religions explain what happens to you when you die. Which one is right? What makes one more right than another? I honestly don't know.

Too many to count, you can even make up a new religion and follow it.