The writing was perhaps complete, but unlike the personal work of Jesus in His own flesh which was finished on the cross [John 19:30] our work, the work in each of us continues until each of us has finished his course [the end of his allotted time].Precisely the New Testament was complete upon johns death
"Looking unto Jesus the author and finisher of our faith; who for the joy that was set before him endured the cross, despising the shame, and is set down at the right hand of the throne of God." Heb 12:2
Our faith when it is finished in each of us will be knowledge, but the work goes on in me and in most of us.
"For I am not ashamed of the gospel of Christ: for it is the power of God unto salvation to every one that believeth; to the Jew first, and also to the Greek.
For therein is the righteousness of God revealed from faith to faith: as it is written, The just shall live by faith." Rom 1:16-17
From faith to faith we move until finally at the end... when Jesus has finished His work in us, then will be able to speak only of knowledge.