This article includes a
Of the customs of the Basilidians, we know no more than that Basilides enjoined on his followers, like
Basilidianism survived until the end of the 4th century as
The descriptions of the Basilidian system given by our chief informants,
The fundamental theme of the Basilidian system is the question concerning the origin of evil and how to overcome it.
 A cosmographical feature common to many forms of Gnosticism is the idea that the
According to Hippolytus, Basilides asserted the beginning of all things to have been pure nothing. He uses every device of language to express absolute nonentity.
 Nothing then being in existence, "not-being God" willed to make a not-being world out of not-being things. This not-being world was only "a single seed containing within itself all the
Part subtle of substance. The first part of the seed-mass burst through and ascended to the not-being God.
Part coarse of substance. The second part of the seed-mass to burst forth could not mount up of itself, but it took to itself as a wing of the Holy Spirit, each bearing up the other with mutual benefit. But when it came near the place of the first part of the seed-mass and the not-being God, it could take the Holy Spirit no further, it not being consubstantial with the Holy Spirit. There the Holy Spirit remained, as a firmament dividing things above the world from the world itself below. 
Part needing purification. From the third part of the seed-mass burst forth into being the Great
Another Archon arose out of the seed-mass, inferior to the first Archon, but superior to all else below except the seed-mass; and he likewise made to himself a son wiser than himself, and became the creator and governor of the aerial world. This region is called the Hebdomad. On the other hand, all these events occurred according to the plan of the not-being God. 
The Basilidians believed in a very different Gospel to that of orthodox Christians. Hippolytus summed up the Basilidians' Gospel by saying: "According to them the Gospel is the knowledge of things above the world, which knowledge the Great Archon understood not: when then it was shewn to him that there exists the Holy Spirit, and the [three parts of the seed-mass] and a God Who is the author of all these things, even the not-being One, he rejoiced at what was told him, and was exceeding glad: this is according to them the Gospel."
That is, the Basilidians believed from
It remained only that the world should be enlightened. The light came down from the Archon of the Hebdomad upon Jesus both at the Annunciation and at the Baptism so that He "was enlightened, being kindled in union with the light that shone on Him". Therefore, by following Jesus, the world is purified and becomes most subtle, so that it can ascend by itself.  When every part of the sonship has arrived above the Limitary Spirit, "then the creation shall find mercy, for till now it groans and is tormented and awaits the revelation of the sons of God, that all the men of the sonship may ascend from hence".  When this has come to pass, God will bring upon the whole world the Great Ignorance, that everything may like being the way it is, and that nothing may desire anything contrary to its nature. "And in this wise shall be the Restoration, all things according to nature having been founded in the seed of the universe in the beginning, and being restored at their due seasons." 
As for Jesus, other than a different account of the Nativity, the Basilidians believed in the events of Jesus' life as they are described in the Gospels.  They believed the crucifixion was necessary, because by the destruction of Jesus' body the world could be restored.   The Basilidian belief was thus that someone other than Christ was crucified instead i.e. Simon of Cyrene