It's rather complicated, and this is a good history of the phenomenon. For a quick answer, scroll to the section titled "Constantine's 'Conversion'"
http://www.bbc.co.uk/history/ancient/romans/christianityromanempire_article_01.shtml
Why did Christianity apparel to many Romans???
4 answers
thanks reed
You're welcome.
Many Romans were drawn to Christianity because they wanted to be a part of a group and the liked the feeling of belonging to something.
-S.S
-S.S