Christianity is about rescuing us from the human condition. And the human condition is one of meaninglessness and purposelessness - in other words it is one of nihilism.
Modern culture is all about happiness, about gratification - about maximizing pleasure and minimizing suffering. Hence, modern evaluations of Christianity focus on happiness - for example whether being or becoming a Christian would be likely to make people more or less happy - happy here and now, or happy over the course of a normal life expectancy.
But this is missing the point completely.
Happiness - of an intensity beyond that of any normal human experience - can, after all, nowadays be purchased for the price of a dose of something like crack cocaine. Admittedly, the longer-term cost of this will be very high indeed. But the point is that crack cocaine refutes the idea that maximizing pleasure is the goal of life.
In the past, for hundreds, thousands, of years - people intrinsically understood that humans were in need of rescue, because human life as such was meaningless and purposeless. We still believe this - or at least that is what the most prestigious philosophers, poets, artists, scientists etc. have been saying for a few hundred years.
Why, then, do most modern people, most of the time, feel no need for rescue?
The answer is simple: distraction. It is not that moderns have found a solution or answer to nihilism, it is not that moderns have transcended nihilism in any way shape or form.
It is instead simply that modern culture has evolved to become incredibly effective at stopping people from thinking about this kind of stuff like meaning or purpose - of distracting, deflecting attention, of providing absorption, of drugging us with pleasures or numbing us with pain, anxiety, distress.
We call this state of continual distraction 'happiness' (or, at least, we call the absence of existential panic happiness).
But Christianity says that distraction per se makes no difference whatsoever to the basic or ultimate human condition - the human condition is the same whether we are aware of it, or are prevented from being aware of it (or prevent ourselves).
The ultimate human condition is the same for us as for the Old Testament Jews, the Ancient Greeks or the Romans - the difference is that we (in our Brave New World) are continuously drugged and numbed, and long-since addicted to the drugging and numbing: I mean really addicted, not just metaphorically.
So Christianity in modernity is in the situation of offering to rescue people from a condition of which they are not aware.