Yep, a key reason why the Romans ate the Greek’s lunch . . . then suffered the same fate once they went down the same path.
Not quite.
The Roman Republic, and later the Empire, was fairly keen on freedom of religion, with the caveat that the sitting Emperor had to be introduced into the pantheon as a “divus” (distinct from “deus”, god), roughly the equivalent of a living saint.
Emperor Constantine allowed the Christians to be exempt from this requirement (as the Jews already were). He personally did not convert to Christianity.
Emperor Theodosius removed freedom of religion by decreeing that Christianity was to be the official religion of the Empire.
Rome fell two generations later in much the same way modern Greece is collapsing.