Mr. Bock, who is Presbyterian, is credited with being the first Hollywood marketer to realize that churches had started to install enormous screens to use during their services, sometimes just to display hymn lyrics. More recently, $35,000 video walls have become more common in sanctuaries. “It makes church feel more contemporary,” Mr. Bock said, adding that ministers are becoming adept at “building vibrant social media communities that expand their reach far beyond Sunday morning.”