I often like to read through the many different Gnostic texts in the Gnostic online library.
I find them fascinating and insightful.
They speak of attaining Gnosis (Knowledge) through spiritual Wisdom, personal experience and perception.
"In a religious context, gnosis is mystical or esoteric knowledge based on direct participation with the divine. In most Gnostic systems, the sufficient cause of salvation is this “knowledge of” (“acquaintance with”) the divine. It is an inward “knowing”
Today I came across a Manichaean Psalm that had familiar feels. 
Taste and Know that the Lord is Sweet
As a note, I am not a follower of any religion, so for me - reading these is never about anything religious.
However, to explain: There are many different systems of Gnosticism, and originally it pre-dated the beginning of what would be modern Christianity. Sadly, a lot of texts are lost, hidden or destroyed and for fear of persecution Gnostic groups were driven into hiding.
So as classical Gnosticism was waning, another Gnostic movement developed under the inspiration of the Prophet Mani. The Manichaean movement became a true world religion, spreading to Europe, Central Asia and China; it survived as a living religion in the Orient up until the present century. So you would find the Manichaean writings have a more typical Christian approach.
The Prophet Mani & Manichaean Writings.
Further reading links on Gnosticism and Gnostic texts.
My personal fave and go to read is
The Nag Hammadi codices (alphabetical order)
In here you will find texts on things like the two creations, The Gospel of Mary Magdalene, The Gospel of Truth, various letters and gospels from the apostles and Knowledge & Wisdom. It also touches on how a woman disciple was the most important and makes you rethink “Church authority”.
Other texts, systems and writings can be found here.
I’ve also included a wiki page about Gnosticism.