The purpose of religion can be seen in Jews

 What we can do is restricted by what we should do and what we must not do. 

It is morality that tells us what we should do and what we must not do

It is religion that instils morality.

Secular political ideologies are also moral systems but they do not have the longevity of religion because they are always less strict than religion on matters of sexual morality.   

The purpose of morality is to keep the group in existence and apart from others. 

Why have all the major world religions required a belief in the afterlife accompanied by the threat of punishment and the promise of a reward? 

This is required in order to restrict the range of permissible actions to protect our group and ourselves eg forbidding murder, theft, sexual immorality and being required to subscribe to a particular narrative to be a member of the religious group.  

Jews are the most successful practitioners of religion because their beginnings were humble: that of being landless fleeing slaves who are now the world's most ancient and powerful tribe believed to be God's Chosen People, who got their homeland back after 2000 years in exile. 

They do not even have to be morally perfect to be God's Chosen People since it is the easiest thing for God to keep them in existence while punishing them, as Zeus did to Prometheus.

They are known for their wisdom because their religion is about learning from their mistakes and reflecting on the significance of their God-given status. They also have a special mission to promote the Noahide laws to gentiles, which many of them seem to deny that they have, probably because they fear to carry out that religious obligation. I have devised a way that will make it very easy for them to do so on social media.   

I will however do it on their behalves by reminding them to rank the four gentile religions according to the Noahide laws.  

My ranking would be to put Islam first because it most closely resembles Judaism and Christianity least because it is blasphemy and idolatry. It is imperative that Christians be warned of the failure of their religion because they are the most numerous of the Abrahamic faiths and they are in charge of a global empire. The fact that many Westerners would deny that they are Christians is another conclusive sign of its failure.