Sikhism does not have a concept of the devil as in Christianity. Sikhs believe that demons are entities which are driven solely by ego. Sikhism teaches that ego is the prime cause of evil doing. Ego has five basic components:

• Pride
• Lust
• Greed
• Attachment
• Anger

Sikhs believe that involvement with ego creates a state of duality. The soul experiences a sense of separation from the divine, which causes all suffering.
Read More:
Unity and Duality
The Five Voices of Ego Defined
Nitnem, the Daily Prescription for Ego