Why is religion especially Christianity so widely practied?

[AFTT47]

A societal system using faith to give hope is very popular for counteracting hopelessness in societies, especially poor ones as Godzilla pointed out. There are also, probably plenty of other reasons such as a structured set of practices for day-to-day life is a was to systematically structure the chaotic world around you. Maybe, a societal group focused on reaching out to people in need is an outlet for feelings of compelling philanthropy. I'm certain there are plenty of others.

I suspect this is very nearly right.  Virtually all religions hold out the promise of 'better things in the next life', which must look pretty attractive to peasants who share a mud hut with various units of livestock.

Boru

Christianity and Islam wield a stick too. The carrot and the stick is an effective combination.