Assert
Part of speech: verb
Definition: To declare with assurance or plainly and strongly; to state positively. To use or exercise and thereby prove the existence of. To maintain or defend, as a cause or a claim, by words or measures; to vindicate a claim or title to; as, to assert our rights and liberties. to make true; to make equal to 1.
Example sentence: Those thinkers who cannot believe in any gods often assert that the love of humanity would be in itself sufficient for them; and so, perhaps, it would, if they had it.
Insist
Part of speech: verb
Definition: (with on or upon) to hold up a claim emphatically.(with on or upon) to demand continually that something happen or be done.
Example sentence: The trouble with having an open mind, of course, is that people will insist on coming along and trying to put things in it.