The Catholic Church (and by extension, Christianity) was started by Saint Paul, who wrote more than half the “Greek Scriptures”. The apostles were still attending synagogues in Acts, so they weren’t out to found a new religion.
I strongly suspect Paul was influenced by the guidance given by Plato in The Republic, as to how to organise a noble religion (eg a god of pure virtue, love and not represented by any animal figure, etc). Paul would have had to have read Plato, given his Greek education. That would also explain why he wrote all those letters to those Greek city states; they would have recognised it and been a little more receptive to the message,