Before 1990, there was only one mortal man in the temple endowment besides Adam and Eve.  This man was a preacher.  His teachings were not the point.  They were not pointed to tell us which religions to avoid. They were an illustration that when man builds his own foundation, he creates confusion, stupidity, mind-numbing dullness, or in other words, darkness.

The point is as Nephi said, we are not to trust any man but on one condition.  Adam demonstrated that he would only recieve messengers from his Father.  Only those who bore the signs and tokens was Adam willing to recieve.

These signs and tokens are not merely what everyone who goes through the temple recieves, for we are the same people when we enter as when we leave.  We have not been proven "true and faithful in all things" by the end of the endowment.

But rather the tokens are proven in those who fulfill their endowment, have the real tokens, and not merely ceremonially bestowed.  Those who bear the Sign of the Son of Man, whether they be God Himself, true angels, or mortals bearing an authorized message, only these was Adam willing to listen to.