The biggest religions in the world (by numbers of adherents) are:-

• Christianity 2.1 billion
• Islam 1.5 billion
• Secular/atheism 1.1 billion
• Hinduism 0.9 billion
• All others 1.3 billion

• Source http://www.adherents.com/Religions_By_Adherents.html

You could try http://www.religioustolerance.org/aboutus.htm for information on the different faiths that exist.

Religions differ in their concepts of deity, other beliefs and practices. But virtually all have passages in their holy texts with something akin to the Golden Rule – treat others as you would wish them to treat you.

The three great monotheistic (belief in a single god) religions of Christianity, Islam and Judaism together account for more than half of the world’s population.  Judaism is relatively small by number – 14 million – but huge by influence, being the precursor of Christianity and an influence on Islam.  It is a great shame that too much emphasis is placed on the differences between these religions and too little on their similarities.

Do kids need a long and detailed moral code?  Or is the Golden Rule enough?  This must be a matter for individual parents’ opinions, but as a starting position it might be good to show how the Golden Rule applies to common right or wrong issues such as stealing, violence, unkindness.

But life is complicated.  Google “Moral dilemmas” and you will find lots of difficult situations where deciding the correct moral course of action is difficult.