The root of sin is deliberate disobedience to God

The root of sin is deliberate disobedience of the laws of nature through disregarding the proprietorship of the Lord. Disobeying the laws of nature or the order of the Lord brings ruin to a human being. Conversely, one who is sober, who knows the laws of nature, and who is not influenced by unnecessary attachment or aversion is sure to be recognized by the Lord and thus become eligible to go back to Godhead, back to the eternal home.

– Srila Prabhupada, Sri Isopanishad Mantra 1