Rational Religion

The Vanishing Efficacy of Theological Argument

Basic rule of human intercourse:  You can't tell a True Believer anything which contradicts his true belief.  The better your proof, the madder you will make him; but you will not sway his conviction.

His anger is likely justified.  Not only are you being presumptuous, you are forcing him into ever more irrational intellectual contortions in order to rationalize his belief to himself.

You are certainly not going to prove anything to him or her.  Physical proofs are problematical in the best circumstances.

I may state something as fundamental as, "The Earth is round."  If a skeptic says, "Prove it!" I am confronted with a complex and impossibly expensive undertaking.  At very least I will have to send him or her on a journey of circumnavigation - accompanied with sufficient instruments to prove distance and direction - until the subject has personal experience of sphericity.

Even then, there is nothing which compels the questioner to believe the (physical) truth.  It could be easier to believe that the entire journey has been an elaborate hoax; almost certainly so if the individual's metaphysical picture of the universe specifically does not include a round Earth.

Of course there is survival value in classical metaphysics.  When a loved one dies there is little comfort in contemplating the physical realities, which are liable to be rather grim and distasteful.  The practiced metaphysician can mentally send the departed one to live in a "better place" under the eternal stewardship of Whatever deity; mourn for a decent interval, and get on with life.