God made provision for Israel to be forgiven for unintentional sins by making a way for Israel to be forgiven, even for those sins that the nation does not know about. Whether an individual or the nation were to sin unintentionally, the sin could be forgiven by an offering of a young bull on behalf of the nation, and a female goat for an individual.
When a person commits a sin presumptuously, though, there will be no provision for forgiveness. Instead, he will be cut off from his people. This sin is related to blasphemous behavior. An being cut off means being killed. Presumptuous sin is serious.
It is understandable that men and women will sin from time to time during a moment of weakness or passion. However, premeditated sin, sin that is planned out and carried out with purpose is a different level of disobedience and disregard for the law of God. While all sin is wrong and grace covers a multitude of sin, it is important to note how God looks at sin. One cannot think that the effects of unintentional sin are the same as presumptuous sin. While a sin of passion or carelessness is evil and trangresses the law of God, intentional sin wreaks havoc with relationships and wounds deeply. Think of the consequences and look before you leap!