Christianity certainly could be lost (as the speaker said) in the West, just like it was lost in major parts of Asia Minor, the Middle East and North Africa. Christianity will always remain in some part of the world.
Christianity will never be lost, because nothing will prevail against Christianity. God is the one who preserves it.
Various countries and cultures, themselves may lose their connection to Christianity and thus not have it as the foundation and basis for their culture or government, but that's not losing Christianity. That is the culture abandoning God. And even so, when the culture abandons God, Christianity still remains, nonetheless.
So, nothing is going to happen to Christianity, but a lot may happen to the countries and the people and the culture who decide to abandon what God has provided by way of His Son, Jesus, the Messiah of Israel.
But, no worries there, because God has already made it clear that He will judge all the nations in the world, including the United States (obviously included in "all" the nations) for its sins and that will happen during the 7-year Tribulation and during the time of the Great Harlot described above, that harlot of false religion, combining forces with the various governments of the world, to bring in the "one-world government" which will be destroyed by the coming of the Messiah of Israel.
I believe that we are in agreement.
It is a matter of semantics.