More can be written, but you might like to start with "Did the veneration of Catholic saints directly transition from the worship of Roman deities?" by /u/thejukeboxhero. As an interest different aspect, you might also like to see their reply here concerning persistence of other pagan practices. Both are from the FAQ section "Non-Abrahamic Influences on Christianity".

This is not to discourage discussion. More questions, data and debate are welcome.