Knowledge (gnosis) is a somewhat more complex concept. Here is the definition of gnosis given by Elaine Pagels in her book The Gnostic Gospels: “…gnosis is not primarily rational knowledge. The Greek language distinguishes between scientific or reflective knowledge (‘He knows mathematics’) and knowing through observation or experience (‘He knows me’).
As the gnostics use the term, we could translate it as ‘insight’, for gnosis involves an intuitive process of knowing oneself… Yet to know oneself, at the deepest level is to know God; this is the secret of gnosis.”(The Gnostic Gospels, p xviii-xix) Bentley Layton provides a similar definition in The Gnostic Scriptures: “The ancient Greek language could easily differentiate between two kinds of knowledge…
One kind is propositional knowing – the knowledge that something is the case (‘I know Athens is in Greece’). Greek has several words for this kind of knowing-for example, eidenai. The other kind of knowing is personal aquaintance with an object, often a person. (‘I know Athens well’; ‘I have known Susan for many years’). In Greek the word for this is gignoskein…The corresponding Greek noun is gnosis.
If for example two people have been introduced to one another, each can claim to have gnosis or aquaintance of one another. If one is introduced to God, one has gnosis of God. The ancient gnostics described salvation as a kind of gnosis or aquaintance, and the ultimate object of that aquaintance was nothing less than God” (The Gnostic Scriptures, p 9).
Faith corresponds to the intellectual/emotional aspect of religion while gnosis corresponds to the spiritual/experiential aspect.