Put one's beliefs to the proof.
Waterproof watches; a fireproof cellar door.
A proof copy of the manuscript.
Proof a fabric against shrinkage.
The batter proofed overnight.
To work on the proof of a theory.
The proof of the pudding is in the eating.
Proof against criticism.
A proof load; a proof charge.
Proof against harm.
An example of proof is someone returning to eat at the same restaurant many times showing they enjoy the food.