Before Cain kills his brother, Abel, he is annoyed that G-d did not accept his offering, but only that of his brother’s.
He is reprimanded by G-d for his inability to overcome his evil inclination and merely making a token, insincere offering. He is told that if he doesn’t improve himself, his passion towards sin will overcome him. This came true when he murdered his brother.
The word for passion used in the Torah is תשוקה. It is not to be understood that passion is a negative emotion. If it is used in the negative, it can lead to crime and corruption.
The Rambam recommends that we should use this תשוקה in a positive manner. We should direct our passion in a David-like manner, in his worship of Hashem. He spoke of how his soul was thirsty for that closeness to the Creator.
He also points out that in order to have that kind of connection to G-d, he must also have such a relationship with his spouse. It must be one of deep love and absolute trust. It would be ideal if one had a rabbi or friend, that he loved and trusted as well.
If one does not have such a relationship with another human being, how could he have it with G-d?
It is also mentioned that the Rabbis decreed a twelve day separation between husband and wife during menstruation. It was in order to increase תשוקה between husband and wife, so that there would be more anticipation for their reunion.
Passion is a very strong emotion. But if it is channeled in the spiritual realm, it can greatly enhance one’s service of G-d, and bring greater joy and contentment.