What are some differences and simularities between...?

Question

Christianity, Greco Roman, and Norse religions?

-Christianity outlived the others how and why?

Answer 1

christianity was much more structured and organized than the pagan religions. also, norse and greco-roman faiths were culturally exclusive and did not seek converts.  

Answer 2

Many people still worship the Old Gods, so Christianity didn't outlive it, they only drove it underground with their persecution, just as they've tried to do with the Jews and others over the centuries.  Christianity, like most religions was simply a new take on an established tradition and as it grew it adapted itself to the local customs to be more acceptable, most of what are now considered Christian Holidays have Pagan origins for that reason.  A detailed analysis and comparison of the Historical relationship between Paganism and Christianity is beyond the scope of this forum, but you might try a web search on "Pagan origins of Christian customs" and go from there.