How to discuss religion with believers?

[Jehanne]

This is just Nonsense on Parade:

Wikipedia -- Bullet Cluster

That's conjecture and uses circular logic.  It doesn't demonstrate dark matter.  It assumes dark matter and uses bullet clusters to try and support that conclusion instead of using bullet clusters to prove dark matter.

If I put out a mousetrap (system), it doesn't prove there is a mouse (object) in the house.  The idea of a mouse doesn't prove the system.  The system proves the mouse by identifying it.  As such we can conclude the mousetrap as an effective system.

And, so, you're saying that unless physicists can weigh electrons on a scale, then, they don't have mass?  Or, their mass cannot be precisely determined?