Why was the Christian faith able to spread? Why was the Christian faith able to spread?

Christianity
spread because it was attractive.  It provided an alternative to the polytheistic status quo,
and it's always nice to feel you're on the cutting edge.  The new idea is always the better
one.  It also allowed people to keep many of the holidays and traditions they liked, just with
some Christian twists.  People like their holidays and they like gradual change in their daily
lives.