Actually, because of demographics, it’s VERY difficult to turn around declining church memberships; usually long after attendance rates rebound, because non-attendees often habitually renew their membership.
Looks like the pentecostalists and restorationists who make up most of the “protestant” denominations have been simply picking the low-hanging fruit of unevangelized, nominal Christians, specializing in class warfare, get-rich-quick schemes (”manna evangelists”), fraudulent miracles, maipulating social isolation.
One whack job on Puerto Rico, with about a million followers, is openly declaring himself the anti-Christ!