The Gospel mandates that we go into all the world, making disciples for Christ, and sharing the Gospel with all of creation, and we cannot fail to do this through every medium, because a medium that is not filled with the Light of Christ will be filled, by definition, with spiritual darkness, the absence of the Light.
Christ did not write the Gospel. Rather, He preached orally, spoke the Gospel face to face and wrote it in the heart and revealed its truths by the Holy Spirit. Christ left us not with a detached message, but with a Body. Even during His earthly ministry He established a broad-spectrum media for His Gospel, first among them, the Apostles (the 12 and then the 70). The Gospel did not live on paper, nor does it now live on audio or video. It lives in human persons who have the Holy Spirit living within them. But the written word has a special place, in that it was penned by people who were inspired by the Spirit of God to keep us in the truth and from straying into false teaching, which is why we refer to the "canon of Scripture." We venerate the Gospels for a reason, because when they are proclaimed, it is Christ Himself and the Holy Spirit Who speak to us. Nothing is self-explanatory, even Scripture, which is one of the reasons why the Spirit came to the Church at Pentecost. That Scripture is not self-explanatory is the reason why we have the account of the Ethiopian eunuch, St. Symeon Bachos (cf. Acts 13.1), in the book of Acts 8.30-31 There we see the question "do you understand what you are reading." The reply is "how can I unless someone guides me?" The Spirit moves in Christ's Body throughout he generations through persons inspired to convey the meaning just as Philip did to the eunuch, and this is above all conveyed in the liturgical services, the living guidance of the Faithful through the prayer of the Church.
It should be no surprise to us that, as God the Father speaks to us by His Word and by His Spirit, that so also does the Word and Spirit speak to us by the Apostles, and that this is passed down through the ages entrusted to others. This is because God established truly a Body. A Body is one whereby the brain operates through the operation of the heart and lungs (breath-spirit). The communication goes through the nervous system (Apostolic leadership) to the rest of the body.
The point is that the rest of the Body can have no doubt that its proper function depends upon the following of the brain's commands, and is dependant to continue because of the operation of the heart and lungs, as oxygen gives a future to the rest of the Body. The oxygen is grace, the commands of the nervous system are the commands of God, and the "nerves" that relay these commands are those entrusted with the commands of God, that they may relay them to the rest of the body.