You cannot know “good” if you don’t know “bad”. You cannot know what it feels like to be in the “light” unless you know what “darkness” is.
The tension created by the duality of opposites, the see-saw of life, allows balance to be achieved. This balance may require you to be so much in the light to feel worthy because you have been in the darkness of unworthiness for so long.
The fulcrum of the see-saw of balance is your reference point. The further down you have gone, the further up you need to go to eventually be in balance. The duality of opposites is continually required to enable you to find your balance and, thereafter, to keep in balance.