I'm Jewish, so Christianity almost seems like cultural appropriation to me: this thoroughly Hellenic religion claiming the Jewish scriptures as its own in order to provide itself with a sense of history & legitimacy. Yeah, sure, Christianity may have started with a man who was executed for claiming to be the Jewish messiah, but it went off the rails very quickly after that. Thanks to Paul, the self-proclaimed Apostle who never met Jesus, we've ended up with this bizarre amalgamation of Hellenic mystery cults, Greek philosophies like Neoplatonism, & Paul's personal theology which were loosely grafted unto the Jewish scriptures & the life of a failed messianic candidate.
Not that I disagree so much, but it should be kept in mind that Second Temple Judaism was very diverse culturally and theologically, and that most Jews of the period were influenced by Hellenistic thought (e.g. Philo, Josephus...). Paul certainly thought of himself as a devout Jew whose mission in converting the Gentiles was to reconcile them to Israel and thereby redeem his people in light of an impending apocalypse. The real split came a generation or two later.
