Sat Sri Akaal,
Sikhism is understanding of ONE truth of inner awareness common and is available to all humanity, but is veiled by developed intellect.
When the Mind is not pivoted or anchored to everlasting TRUTH mind has belief of duality and there is multiplicity, resulting in formation of deras, sects, and many other formations, devoid from understanding of universal and internal awareness.
Though having the positive role and glorification. Negative aspects of not pivoting the thought to Origins and original concept has given rise to division at philosophy level which manifests in outer realms.
So those who attained realm of everlasting TRUTH are united.
It's ONE and multiple of ONE but not two or more.
Without understanding of Mool Mantra ie Original Syllable.
Ik O Ang Kaar. From One Cell there is multiplicity and is doer. Is Origin and Original concept for all learners to follow.
Waheguru Ji Ka Khalsa
Waheguru Ji Ki Fateh