Does it claim those things, though? Forward looking and optimistic? For one thing, 99% of the game doesn't even have anything to do with a future. BNW tried to make the late game interesting by ensuring that it'd lead to a long term world war scenario (unless one Civ can disrupt the balance of power and gain control over all of the other civilizations.) And the original Civ introduced rampant pollution in the late game to reflect the result of our modern accomplishments.
I'm not particularly enthusiastic about a religious victory (although I'll wait to find out what that means before judging it), but the main story of Civ isn't at all optimistic IMO. From Civ I, it's been about either conquering Earth or escaping the Earth ruined by humanity's wars and overdevelopment to try to rebuild society on Alpha Centauri.
Yes it does, Civ4's civic selection, the downplaying of religion in the late game, and it's really ramped up within every Civ5 intro video, G&K/BNW's inflection away from religion, and the Civ6 preview video.
The focus was more jumbled in the old days, but in the last 10 years since at least Civ4, it's all about 'test of time' stuff and taking a stance about being very pro-science and progress.
Religious victory, especially in the western context, would be a step back.
I can see religious victory as being a subset of the new diplomatic but not diplomatic victory since Ed himself confirms he's going to allow players to play in set-eras only and not through the whole timespan, and that sense you can have a religious victory in a game that ends in the renaissance.
RE: Stealth_nsk's comments about the government's cynical use of religion to gain power and execute geopolitical agendas and suppress dissent, I don't see that as an element of religious victory, but as a way religion may be transformed in the late game as a pure diplomatic tool to leverage what you did in the early game. It could well be part of the new VC. Since we've got the peaceful builder and the warmonger VCs pretty much covered, the space left by diplo would be something relating to city-state votes, and influence over other Civs (declaring war without going to war).
I just still don't quite see it in the main 'epic' game.