Actually, according to the CNA, the number of the “faithful” has remained pretty steady around 17.3% with growth in Africa and Asia and declining in Europe. (
catholicnewsagency.com/news/global_catholic_population_remains_steady_africa_and_asia_continue_growing/)
Faith, manifest as simple habituation by osmosis from one’s family and peers, is a simple condition necessary for survival in one’s “home” group. It becomes obvious as one’s circle of comprehension grows that one’s beliefs, customs, etc, vary, sometimes wildly, from those of others. A part of becoming mature is the growth away from infantile ego and the stages that follow that in spite of the tendency of a mind to argue its particular way as being THE correct world view.
So there is no one, really, who does not have some variation of tunnel vision, even (Oh-my-God!) Catholics.

So overcoming tunnel vision of any variety is a matter of maturity and personal growth incumbent on everyone of any derivation, and it is not strictly a religious or secular matter though we might try to narrow it to one of those. We might employ that tunnel vision idea especially when we hear
any bit of belief that we do not agree with. But the thread title reminds me of the idea of casting the log out of one’s own eye before attempting to remove a mote from another’s. And we might remember in the mean time that just like we grew up and necessarily adopted our own views, religious or otherwise, so did the person we attribute limited vision to. So maybe that other person is a mirror, reminding us to check our own prejudices as to what’s “right?”