These are strong warnings!
Mankind has an innate desire to worship God, but he wants to be free to do it according to the dictates of his own mind. The result is a wide variety of religions—in actuality, mass confusion as to which is the true religion—and a world in which true values are lost in an ocean of conflicting opinions about how to live. This, in turn, has helped persuade many people to reach the conclusion that all gods are equally good, or its counterpart, that everybody is worshipping the same god.
We all know God is not pleased with this situation, but He allows it to continue. However, even while allowing it to continue, He is calling people out of it. He has shown His called-out ones that they have been redeemed from the bondage to traditions, described in I Peter 1:18 as "vain," "aimless," or "futile," depending on the translation. However, in the vast majority of cases, someone, presumptuously taking it upon himself to inaugurate a tradition, began practicing them, sincerely thinking he was improving his life. We have all followed these traditions, but the Christian is responsible not to allow the world to squeeze him into its mold of conduct, character, and attitude.
Proverbs 21:16 describes the way many presumptuous sins begin: "A man who wanders from the way of understanding will rest in the congregation of the dead." Like this man, most people do not deliberately set out to depart from God. Nevertheless, carelessness invariably enters the picture, and a person drifts from his former sure fix on his goal. Once his focus on the goal is blurred, he is more easily deceived into foolishly assuming certain things. An especially sad part of this is that the result is the same as if he were deliberately presumptuous.
The author of Hebrews uses a metaphor in Hebrews 2:1-3, portraying a boat slipping from its moorings and drifting away. A person "neglect[s] so great salvation" by allowing himself to be caught in the current of the world's attitudes and conduct. Presumption frequently begins with careless drifting, but the drifting quickly advances from neglect to presumption unless one carefully checks whether he actually has God's permission to behave as he does.
In Proverbs 8, wisdom is personified as a woman crying out to people along the way—to God's Kingdom?—to take heed to her instruction. In verse 36, she utters a profound warning: "But he who sins against me wrongs his own soul; all those who hate me love death." None of us likes to think of himself as foolishly loving death. However, the Bible consistently shows that those who do not consciously, purposefully, and carefully direct their lives toward obedience to God do indeed love death rather than life! Such a person is in effect presuming that all is well with him in relation to God. God does not like being taken for granted—because it is bad for us!