unwavering

And on this occasion she [Lady Mary, later Mary I of England] wrote the king a letter (which these noblemen seem to be the carriers of) chiefly to shew how unwavering she continued in her formerly declared purpose about religion; […]

For, foraſmuch as Faith properly ſo called is nothing but an unvvavering Aſſent to ſome Doctrine propoſed upon the ground of infallible Teſtimony, there muſt be ſome Reaſon to perſuade us that that Teſtimony is infallible; […]