Most Christian rock bands explicitly market themselves as such, rather than seeking a wider audience. Presumably, they see their music as a form of proselytizing. U2 doesn’t do that. But so many of their songs are about a relationship with God that they certainly could have gone down that path.
The record was a deliberate attempt to return to the earnest rock style of The Joshua Tree — the style that catapulted the band to superstardom in the first place.