Sexual impurity - why is it so bad?

In the Western world, people make fun of 'superstitious religious nonsense' about spilling seed. Western society teaches that it's great, fine and even healthy to spill seed. The main problem is that Western society doesn't believe in souls or the afterlife. Once we believe that the soul is a reality, and an integral part of each human being, we can start to understand why spilling seed is so bad.

In a nutshell: Each sperm contains its own potential soul, with all the different 'soul' levels of nefesh, neshama, ruach etc. When a person sins, a part of their soul's 'energy' is captured by the forces of darkness, and is used to power destructive forces in the world. When that person subsequently repents for their bad deed and makes teshuva, they repatriate that part of their soul's energy for good, and it can once again be used to build a new world, instead of destroying it.

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The tremendous spiritual energy from all these 'wasted drops' goes directly to power the forces of evil in the world. Once these souls are captured by the forces of evil, it's very hard to free them, and they will do everything in their power to avenge their horrible situation by attacking their 'father', in whatever way they can, including trying to 'steal' his energy, confusing his mind, filling him up with heresy and other evil thoughts, and making him thoroughly depressed, miserable, mad and 'disconnected'.