actually in refrence to the keltic culture and their gods being twisted wasn't that christianity lacked it's own dogma...but rather more of a tricking of the masses...They never "christianized" rome that's why you can still see many of their alters and statues to honor their gods intact..however i don't know the history of rome and christianity as well as the kelts...

by time the christians made it to the keltic nations they tried to get them to convert, but being deeply religious sort of people they found they would go to the same places to worship the same deities...so christianity "readjusted" their practice to coincide with the kelts...and it worked...by building their churches on keltic holy places, renaming their gods to saints and celebrating their holidays with a christ spin they soon had the kelts "christian" yet the kelts still saw it as "their" religion...that's why there are so many crossover between ancient keltic worship and christianity...christians didn't intentionally steal themes, they were just tricky about it.