श्रीभगवानुवाच | काम एष क्रोध एष रजोगुणसमुद्भवः | महाशनो महापाप्मा विद्ध्येनमिह वैरिणम् ||३७||
śhrī bhagavān uvācha kāma eṣha krodha eṣha rajo-guṇa-samudbhavaḥ mahāśhano mahā-pāpmā viddhy enam iha vairiṇam
Translation
The Supreme Personality of Godhead said: It is lust only, Arjuna, which is born of contact with the material modes of passion and later transformed into wrath, and which is the all-devouring sinful enemy of this world.
Interpretation
The answer is direct and unambiguous: the cause of sin is kama (desire/lust). When desire is frustrated, it transforms into krodha (wrath). Both are born of rajas (the mode of passion). Desire is 'mahashana' — the great devourer — and 'maha-papma' — the great sinner. Know this as the enemy. Naming the enemy correctly is the first step to overcoming it.