Christianity isn't collapsing, it's killing itself and everyone else.
But there is a breathtakingly simple solution:
STOP JAMMING YOUR F***ING RELIGION IN EVERYONE ELSE'S FACES.
No one "persecutes" Christians in this country because it's not persecution if it's self defense. Christians are trying to take over the country and seize control of the levers of power over the objections of the majority. If you guys could put down the martyr complex and commit yourselves to a live-and-let-live philosophy then you'd be left alone to do whatever you do in peace.
You.Are.The.Persecutors. How in God's name is that a mystery to anyone???