'CCL' is a frequent and thoughtful commenter at this blog, often providing analysis and clarification. This comment deserves special attention:
Nihilism is so prevalent because the universe itself is nihilistic.
This is the primitive Judeo-Christian doctrine found in Genesis and reiterated throughout the Old Testament, which forms the context on which the New Testament has real significance.
Simply put, it is not easy for God to create meaning and hope in a universe that is fundamentally inhospitable to such things. Platonic Idealism and Post-Christian thought cling to the assumption that there must be meaning and hope in life, but Christianity itself only makes sense when you accept that there is nothing logically necessary about your life meaning anything in the end.
That's the initial attraction to believing in God at all, let alone Christ, so that there will be someone who cares about your otherwise pointless existence (who will not simply die out meaninglessly in turn).
Nihilism doesn't come from false metaphysics so much as from a lack of metaphysics.
But when you have incomplete metaphysics, in which the positive metaphysical assumptions do not include all that is logically entailed, then the remaining metaphysics are false. When someone assumes that their own life has meaning and purpose, but does not accept the metaphysical assumption that makes that possible, then the (otherwise true) assumption that it there is meaning and purpose (or even coherence) in life is rendered false.
For someone in this position, it is useful to be confronted with the real alternatives, if they do not believe in God they cannot really believe in anything at all. They can merely willfully entertain a delusion of unsupported meaning.
Some may at that point decide to go ahead with believing nothing at all. But most won't.