He’s talking about “protect[ing] Christianity” so neither seem to fit. Quoting the First Amendment would be a better choice since that’s the operative document except it doesn’t speak of protecting a religion only the free exercise of it.
Others have drawn the tie between the name of the university and the word “liberty” in some translations of the verse. Seems forced because he’s speaking to “religious people.”.
It’s a pretty good University! Where the Spirit of The Lord is, THERE is Liberty. Liberty University is a CHRISYIAN University.