Q. When someone moves from orthodoxy to heresy how far can they go?
A. All the way to hell.
That is shockingly blunt. You ought to read the question and answer again with what Packer calls a "traumatic awe." We do not want it to be so, but we are not fit to arbitrate on these matters or to run the universe.
Orthodoxy is serious. Heresy is serious. Neither are playful word games.
"...just as there are doctrines that are true, and that can bring salvation, there are those that are false, so false that they can spell eternal damnation for those who have the misfortune to be entrapped by them."
Harold O. J. Brown, Heresies, p. 4