Christianity IS growing in population.
With over 1200 Christian organizations, the USA has a greater number of Jesus fan clubs than any other country in the world. The proliferation of variegated brands of Christianity in America is so extreme that it acquires a comic dimension. One might discern only a subtle difference in name between, say, the "Evangelical Congregational Church" and the "Evangelical Covenant Church", or the "Church of God in Christ" and "Church of Christ" but miss a gulf of doctrinal distinction.
But then, who is bothered about doctrine anyway? Denominations, a source of so much anguish and bloodshed in the past, have diminishing importance in the era of evangelical psychosis, mega-churches and apocalyptic blockbusters. The important thing is to "have religion". "With religion" you are a patriot, defending the American way of life; without religion you are a subversive radical, an enemy.
Christianity USA is all show business and emotional razzmatazz. Organised as international corporations, with a globalised "mission" of subsidiary offices, its product is propaganda, pouring in prodigious quantity from a network of TV and radio stations and publishing houses. The intent is to draw further millions into the mass of devotees.
In choreographed extravaganzas Pastor whips up mindless love of Jesus and serious fund raising, and then retreats to his opulent sanctuary, content in knowing that he is a tireless servant of the Lord.
"So what did God do? He GAVE the very thing He needed – His only begotten Son, the best gift heaven could give! What did God receive? Yes, we know – billions of sons and daughters! God lives by His own law – you GIVE if you expect to RECEIVE!"
– Paul Crouch of the Trinity Broadcasting Network espouses the "theology" of fleecing the sheep on behalf of a needy God.