What would the impact have been if a few hundred years before Captain Cook happened by there had been a Hawaiian Martin Luther who led a Reformation of the religion?
Let's assume it would be not completely different, but more moderate. For example, it would not have suddenly claimed that there's only one God. But perhaps human sacrifice might have been eliminated. Kapu laws might have been softened, keeping bans on eating certain fish at certain times of the year (to prevent depletion of resources) but allowing men and women to eat together.
Would Ka'ahumanu and Liholiho still have abolished the religious establishment?
Would Hawaiians have been less likely to accept Christianity?
Would cultural conflict between Hawaiians and Westerners have been reduced? or increased?