While Islam is the fastest growing, and Nones more so than Christians: http://peacebyjesus.witnesstoday.org/RevealingStatistics.html#Sec2
If by the “church” means the building and the priest, then Catholics are probably not broadly well fed, when they attend only weekly on Sundays. If they were poorly catechized growing up then yes, they are probably found spiritually wanting today.
Sundays in the evangelical churches are rousing, spiritually experiential, with soaring senses, so a poorly fed Catholic ex is comforted there in his own relationship with his God.
On the other hand, for all her flaws and spiritless priests giving boring homilies, there she is, still standing. Christ’s Church. He is there within her, in His tabernacle to be consumed, transferred from the hands of the hands, of the hands of the Apostles themselves to my lips. Beating that? Just impossible, IMHO.
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And I understand that Islam is the fastest-growing “faith” in America now. Pretty terrifying.