What was the appeal of christianity in the early 4th century. What was it's main message and what made people so interested in it?

3 answers

http://www.pbs.org/wgbh/pages/frontline/shows/religion/why/appeal.html

http://en.wikipedia.org/wiki/Early_Christianity
so basically people were promised spiritual gifts and what not?
Yes. I think everlasting life was another appeal. The prospect of life in heaven made it easier to bear the hardships in life.