A postulate is a statement that is assumed true without proof. A theorem is a true statement that can be proven.

How much does a postulate have to be proven?

Postulates themselves cannot be proven, but since they are usually self-evident, their acceptance is not a problem. Here is a good example of a postulate (given by Euclid in his studies about geometry). Two points determine (make) a line.

Can a postulate be accepted without proof?

An axiom or postulate is a statement that is accepted without proof and regarded as fundamental to a subject.