With A Course in Miracles as a guide, this element of Jesus' teaching, and of perennial wisdom, really, becomes much clearer. And by going back to basics, we can untangle the Book of Thomas, and much else that Jesus said, from the colorful gnostic theologies of the second and third centuries CE, which often times go well beyond the intentions of the original teachings, and accordingly we can read it in its original sense.
What becomes clear is that to quote a Biblical tradition, "to those outside the Kingdom" it all comes in parables--we who are identified with duality, who think we are separated individuals, and outside Heaven, the Kingdom, or the Oneness of the Mind, of necessity perceive the world in those terms, and perceive individual identities around us. That is the state of unknowing, where we see others as we see ourselves, because we project the separation thought, and the realm of perception is merely designed to confirm that projection and make it real. It is when our false self sees naught but false selves, and deems that reality.
The state of knowing (knowledge in the Course) means to know ourselves to be as indeed God created us, as spirit and one with Him, which goes hand in hand with seeing the face of Christ in all our brothers, for now we recognize our true Self in everyone we meet and we operate in Love and from Love. This is the state of knowing, knowledge, gnosis.
In short, all the theological explanations of the word gnosis in the end go back to a very simple and basic concept that Jesus taught from the beginning. It is the core of a non-dualistic thought system for only in complete oneness does the concept of total certainty exist, that certainty is gnosis. The knowledge of the world deals in degrees of "certainty," but never in total certainty, and therein lies the rub. More information can reduce uncertainty, but this is a limiting function, and "certainty" can never be reached, because it is not in the perceptual domain by definition. It is not of this this time/space continuum. That is why Jesus said: My Kingdom is not of this world. Some of the Thomas Logia may now be clearer:
J said, "If your teachers say to you, 'Look, God's Divine Rule is in the sky,' then the birds will precede you, 'It's in the sea,'then the fish will precede you. Rather, God's Divine Rule is within you and you are everywhere. When you know yourself, you will be known, and you will understand that we are one. But if you don't know yourself, you live in poverty, and you are the poverty." (Logion 3)
I stood in the world and found them all drunk, and I did not find any of them thirsty. They came into the world empty, and they seek to leave the world empty. But meanwhile they are drunk. When they shake off their wine, they will open their eyes. (Logion 28)
J said, "Let one who has found the world, and has become wealthy, renounce the world." (Logion 110)
The disciples said to him, "When will the Kingdom come?" He said, "It will not come by watching for it. It will not be said, 'Behold here,' or 'Behold there.' Rather, the Kingdom of the Father is spread out upon the earth, and people do not see it." (Logion 113)Each one of these expresses the contrast between the world of ten thousand things, and the oneness of the Kingdom, the contrast between knowing many things, or pure knowing, gnosis. To be drunk on the knowledge of a great many things would prevent you from knowing yourself, and thus having gnosis.