The struggle between good and evil begins with creation. As does the need for "Tikum Olam", bringing the world to G-dliness. Because creation appears independent of a creator, we experience two realities instead of one: creation & Creator.
This duality represents a loss of oneness, it introduces the G-dly and the ung-dly, which then deteriorates to good and evil. Part Two of Tanya ( Shaar Hayichud ) teaches us to see the truth of creation. He is everything and everything is Him. Part Three of Tanya (Igeret Hatshuva) illuminates the subject of Teshuvah, forgiveness and reconciliation.
