What did the Greeks who Paul taught believe?

When Paul went to teach the Greeks he had to overcome some serious hurdles. The Greeks believed in multiple human-like gods (such as Hera, Aphrodite, Ares, and Zeus) who were temperamental and required acts of piety or risk retribution. There was no organized religion with clergy or scripture.

Paul therefore had to convince these Greeks that there was one, loving God with a Son who sacrificed His life for humans. This God required them to not just perform rituals but to change their very nature (Source).