So, we have a Crystal Dragon Jesus cult which has something purely metaphysical as a Crystal Dragon. Let it be the Church of the Moon Goddess. Then we invent spaceships, fly to the moon and meet the Moon Goddess herself; she's very glad to see us and is actually as beautiful and benevolent as we thought. That's the trope: a correct scientific proof that the religion is right. Note that the proof must be correct in-story, it doesn't have to make any sense in Real Life. Note also that merely having a Physical God doesn't qualify: You must have a faith-based religion prior to the divine encounter.