There's not really a problem with the 'true meaning of the word' religion - the 'problem' is that many misuse the word 🙂

The start of religion is very much a chicken and egg situation - as Harry's link suggested one reason for the introduction and take up of a religious belief is that doing so introduces a structure to a loosely grouped society, allowing its growth by introducing a moral structure and possibly even more importantly assisting in the formation of a military with soldiers willing to die for their Gods.

The other scenario is that a stable society provides the opportunity for the establishment of tradition and a 'priest' class.  Belief by an individual in a superior being is superstition - that same belief practiced by a group is a religion.

I tend to go with the former scenario - all the 'successful' religions have been patronised by the ruling classes, those that aren't continue with a small number of adherents and tend to be classed as cults rather than religions.  Christianity only really 'took off' following Constantine's approval which coincidentally came about at a time when he needed his army to be successful. 

Judaeism became the established religion of the Jews when Moses needed to control an increasingly restless population. 

There is a general misunderstanding that Islam as a religion started with the prophet Muhammad whislt in fact the Islamic religion was aready in existence when he was born with Noah, Abraham, Jesus etc all prophets of Islam.   Following the prophecies and teachings of Muhammad the Islamic Empire saw a period of rapid expansion taking in most of the Middle East, North Africa and Spain.