Well, a helpful place to look is Geerhardus Vos' article "'True' and 'Truth' in the Johannine Writings." In that article, Vos helps to show that John uses these terms in relation to Jesus and who he is as the eschatological savior come from heaven to earth and as such, his words share in his "otherworldliness." The truth of Christ and his words has more to do, then, than just speaking of their trustworthy character; his words are heavenly and come from heaven as he did. As such, Christ abides in his people through his truth--truth that is bound up with his word, the Bible. Here are a few snippets:
When Jesus is called “the truth,” it would be a rash judgment to assert that this can mean nothing else than that His words are the supreme, incarnate veracity. The noun can just as well mean, and undoubtedly, in view of the usage of the adjective, sometimes does mean, that the supreme reality of the things that compose His character is incarnate in Him. The fulness of “truth,” which, side by side with “grace,” resides in the Only Begotten, must mean far more than the reliability pertaining to His words;
It cannot be otherwise than that the words of Him who is by nature and origin the “veritable” One should partake of the same character precisely because they are His. His kingdom is not of this world (but of the heavenly world), and for this very reason He came from the higher into the lower world that He should bear witness unto “the truth,” and that every one that is of “the truth” should hear His voice (18:37).
He is simply “not of this world.” And what is true of Jesus is, of course, on the principles of the Johannine teaching throughout, in the statements both of Jesus and of the Evangelist, applicable to the disciples, for in no document is the identification of Jesus with the believer more emphatically affirmed.
What is practically involved is the principle of ultimate spiritual value in regard to destiny. The practical name for this is the principle of “otherworldliness.”
The life of faith is not just about trusting Christ's word, though it does include that, but it is about trusting that his word is at work within us binding us to him so that we understand that the heavenly life of Christ has intruded in us now and is working within us until we enter in to the full consummation of our heavenly inheritance. The truth of Christ shares in Christ's nature and therefore binds us to him, which comes to us in the form of an anointing. So, as the anointing you received from him abides in you . . .and is true . . . abide in him (1 John 2.27).
You can find the article in Vos' Shorter Writings, or read the entire article online for free here.