Chief Rabbi Lord Sacks opines that religion survives despite its functionality being replaced by modernity because:

My answer is simple. Religion survives because it answers three questions that every reflective person must ask. Who am I? Why am I here? How then shall I live? … You can take science, technology, the liberal democratic state and the market economy as four institutions that characterize modernity, but none of these four will give you an answer to those questions that humans ask.

Sadly, what that boils down to is a fear of death. Finding meaning is part of that, as meaning gives a sense of fulfillment in the face of departure (having children or leaving works to be remembered by accomplishes this as well, but those also can be fulfilled without religion).

Ultimately, we sense demise as oblivion, and fear it like nothing else. Religion gives us an escape from that which horrifies us to our core–and thus explains why, then, people become so intensely charged when their religion is challenged or questioned. Tearing down even a part of that structure is, to many, equal to tearing it down as a whole; this explain why, when confronted over even trivial matters, some religious folk become highly offended and extraordinarily defensive. You’re not just questioning one part of scripture, you are, emotionally to them, trying to deprive them of their comfort in the face of absolute demise.

What would truly challenge religion is not science, doctors, credit cards, or psychotherapists. Instead, people facing and coming to terms with their mortality would accomplish that. To find solace and satisfaction with the fact that you have existed at all, the gift that life is all in itself, or even to know that oblivion would carry with it an end to even fear. If we could find a way to instill a comfort with mortality, religion would take a serious hit.

But not a mortal hit, because there is one other major reason religion survives: tradition. People passing religion on because they were immersed in it from their birth onwards, like an ancestral home. That all in itself has a powerful inertia, a momentum that could not easily be stopped.