Christianity is the majority religion today, and has been for 1700 years (or so).
Something has to be special about it... or not?
From the christian perspective, the answer is easy - it was god's plan all along, so of course christianity is the winner.
If you don't believe in it, then there must be other explanations. What are they?
Christianity promises salvation from sin, from self, sanctity.
"Christianity came into favor in Rome at a time when there was great contention between the vigorous teachings of the Stoics and the salvation promises of the mystery cults. Christianity came with refreshing comfort and liberating power to a spiritually hungry people whose language had no word for “
unselfishness.”
That which gave greatest power to Christianity was the way its believers lived lives of service and even the way they died for their faith during the earlier times of drastic persecution.
The teaching regarding Christ’s love for children soon put an end to the widespread practice of exposing children to death when they were not wanted, particularly girl babies.
The early plan of Christian worship was largely taken over from the Jewish
synagogue, modified by the
Mithraic ritual; later on, much pagan pageantry was added. The backbone of the early Christian church consisted of Christianized Greek proselytes to Judaism.
The second century after Christ was the best time in all the world’s history for a good religion to make progress in the Western world. During the first century Christianity had prepared itself, by struggle and compromise, to take root and rapidly spread. Christianity adopted the emperor; later, he adopted Christianity. This was a great age for the spread of a new religion. There was religious liberty; travel was universal and thought was untrammeled." UB 1955