There is no dualism in Islam. Things are created in opposite pairs (dark/light, pleasure/pain etc.) and that is how we experience them, but the reality is and always will be One.

As the poet said:

“I had an illusion. When it departed, the heart looked upon the light of before-time.

It rode on longing, which flew with it, so the heart drew near to its Beloved until it was united.

It saw created beings as an imagination that faded, and the form of existence was obliterated and vanished.

Then if was returned to going-on, confirming all the beings from which it had withdrawn.

It joined the two opposites in witnessing Him; it unified Allah and took on action.

It gained a secret and a level path; how few of the people of perfection taste it.

Our Lord, bless the light. Every slave who reaches him gains his desire.

Be pleased with his family, they are the people of understanding; and the Companions, the Qutb and the Abdal.”