Is metaphysics important to being a Christian? Here-and-now it is Vitally important

Metaphysics is discourse concerning our fundamental assumptions regarding the nature of ultimate reality. 

It was the case through much of Christian history that disagreements about what was fundamental reality didn't make much difference to being a Christian; because all the necessary assumptions are natural to children - hence were common to pretty much all of humanity. 

But things have changed. 

In our civilization (which dominates the world) the fundamental assumption underlying all of our official and public discourse is that everything-that-is, the universe, arose without purpose as a consequence of physical "laws" plus "randomness". 

Most of this universe, the ultimate particles, elements, compounds; water and rocks and gases; are not alive...

So life, consciousness, Mankind - inhabits a dead reality that has no purpose or meaning. 

We need to be clear that these modern assumptions are neither spontaneous nor natural; all have been deliberately and elaborately inculcated and are sustained via social systems - education, employment, mass media, propaganda etc.   

This is probably the main reason why Christianity - and the other religions - is almost entirely absent from the world, and especially from The West; and feeble when it does exist.

Christianity contradicts our fundamental understanding of reality.  

In other words; Christian faith tries to survive as a thin film of psychologically-asserted purpose and meaning, life and consciousness - floating on the surface of a world-pervasive metaphysical assumption of death and nothingness.

So Christianity is rootless, unmoored, adrift; and strikes the modern person as arbitrary-believing, wishful-thinking, and/or psychological mass manipulation.  

Which would be true if modern metaphysics was valid. 

As we find it, here and now; Christianity is both rare and weak.  

The implication is that - unless we focus-upon and evaluate our fundamental assumptions regarding the nature of ultimate reality, and reject them - then Christianity will be contradicted by our deepest beliefs. 

Unless we know, reject, revise our metaphysics - Christian evangelists are wasting their time because real Christianity is doomed. 

Lacking which; even when Christianity is asserted, it will be incoherent with life and society, therefore experienced as irrational and honestly-indefensible.