Well, considering the Psalms and other Old Testament canticles, such as Benedicite Omni Opera (the song of the three children who Nebuchadnezzar tried to burn in a furnace, but an Angel or possibly Jesus Christ appeared with them and they were protected), and the Songs of the Suffering Servant in Isaiah, are essential parts of Christian hymnody, and the Summary of the Law given by Jesus Christ includes what is basically the Shema, which is the Jewish creedal hymn and the basis for the First Commandment of the Decalogue (followed by the Golden Rule), and given that the Aaronic Blessing is commonly used in church liturgies, for example, as our friends
@MarkRohfrietsch and
@ViaCrucis will confirm, it is the dismissal for several traditional Lutheran liturgies, I would feel close to the way I feel.
However, just as the Torah or Pentateuch is the most important part of Scripture to the Jews, for Christians of traditional theological views, the Gospel is central, and that Gospel has been handed down in four canonical books, with the purpose of the Epistles being to expound upon the doctrine and theology, and of Acts to show the work of the Holy Spirit amidst the disciples, and of the Apocalypse (Revelation) to provide an eschatological and mystagogical vision and also to allow those messages St. John the Beloved Disciple received from our Lord to be communicated.*
The important thing is that these Gospels represent the keystone of Sacred Scripture, because they discuss the incarnation of God Himself, when the Divine Logos, the Only Begotten Son and Word of God, became human, putting on our nature and uniting it hypostatically with His divine nature, without change, confusion, division or separation. And thus what Jesus Christ, whose name can be translated as The Messiah, YHWH (who) Saves (Us), and who is also called Emanuel, meaning God with Us (El or Elohim being the generic Hebrew word for God, and YHWH, “I AM that I AM” being the proper name of God,
does and says in the four Gospels, is nothing less than the central part of the Bible.
Ergo, when our Lord, God and Savior teaches us how to pray in the Gospels According to Matthew and Luke, that is extremely important. That St. Paul doesn’t repeat it is irrelevant, because St. Paul’s epistles were not selected because they repeat the Gospels but rather because they, along with the epistles of the other Apostles, Saints Peter, John, James, Jude, and the unknown author of Hebrews, provide the material needed by the Church to reinforce the Gospel through exegesis.
It is also worth noting that just as St. Mark was a disciple of St. Peter, St. Luke was a disciple of St. Paul, and since, unlike St. Matthew the Apostle and St. John the Beloved Disciple, they were not present at most of the events in the Gospels, St. Mark recorded St. Peter’s recollection of events, and St. Luke recorded a recollection of events that had been aggregated by St. Paul based on his interaction with other the Apostles and the Christophany he experienced on the Road to Damascus.
Additionally, I strongly believe Chapter I of the Gospel According to Luke was narrated to him by Our Lady, the Theotokos and Ever Virgin Mary, for tradition establishes he was a physician and painter, and specifically looked after St. Mary in Ephesus and painted a portrait of her, now lost; this makes even more sense when we consider that our Lord on the Cross had His mother adopt St. John the Beloved Disciple (who was likely the youngest apostle; I believe he was in his early teenage years based on the conventional dating of the Gospel of John to the late 70s, and the Apocalypse to 90 AD, and his repose from natural causes in 93 AD (he was the only one of the Eleven Faithful Disciples not to have been martyred but to die peacefully of natural causes); he was also the mentor of St. Ignatius of Antioch, who was fed to lions around 105 AD in the Coliseum, and St. Polycarp of Smyrna, who was himself martyred at around 90 years of age around 150 AD, and St. Justin Martyr and St. Irenaeus of Lyons were their disciples). St. John in turn became the Bishop of the Church in Ephesus, which St. Paul seems to have had far more praise for, and fewer problems to address, than the others he visited and wrote epistles to, and St. Luke and St. Mary were said to have lived in Ephesus, and it was there she reposed and was translated bodily into Heaven, which is commemorated on the Feast of the Assumption, also known as The Dormition, on August 15th.
Thus, the Four Gospels are the vital beating heart of Sacred Scripture and Holy Tradition, with each Gospel being like one of the four chambers of the heart, and thus what they say defines the meaning of the rest of Scripture, as we read at the end of the Gospel of Luke, when our Lord opened the Scriptures (which at the time were the books of the Old Testament, since it would be 20 year before the oldest parts of the New Testament, and showed the remaining eleven disciples they were all about Him, and the same is obviously true of the other books of the new New), and furthermore, one of the two Evangelists to record the Lord’s Prayer had a special relationship with St. Paul, a biography of Paul being a major part of Acts, and the Blessed Virgin Mary and her adopted son St. John the Beloved Disciple, since Saints Luke, John and Mary lived in Ephesus, where St. Paul frequently visited, this shows the Lord’s Prayer happened, St. Paul knew about it, probably from St. John, and St. Luke recorded it. St. Paul in turn regarded the Church in Ephesus as exemplary, and the four most important Patristic figures of the second century were disciples of St. John (St. Ignatius of Antioch, St. Polycarp of Smyrna, St. Justin Martyr and St. Irenaeus of Lyons). Thus we can say that St. Paul approved of the Lord’s Prayer and regarded it as generally applicable, just like the other teachings of our Lord, for example, the Eucharist, the Institution Narrative of the Last Supper being recorded in the three Synoptic Gospels and in 1 Corinthians XI, and the Eucharist being described as a sacrament vital for our salvation in Chapter VI of the Gospel of John.
*Indeed, many scholars refer to the books penned by St. Luke the Evangelist as Luke-Acts; I think we should also talk about the Apocalypse as being a direct followup to the Gospel of John; of course the normal practice is to talk about the Johannine Corpus to avoid deprecating the Epistles, which is important, but there are too many revisionists trying to claim someone else wrote the Apocalypse). And of course, the Gospels of Matthew and Mark are standalone writings, but each of the four canonical Gospels forms a mosaic that teaches us about the life of our Lord.
There may have been a fifth legitimate Gospel of Peter, but unfortunately only a fragment concerning the Passion and the Empty Tomb survives, which is interesting, but insufficient to dispel concerns of some bishops that it had a Docetic heretical aspect. I hope one day a complete manuscript of it, and Origen’s Hexapla turns up. The former is likely useless, but the latter would be genuinely interesting. As for the other apocryphal “Gospels”, I think the Gospel of Thomas is a corruption of a list of sayings written down by the disciples of Thomas, Addai and Mari, in Syriac, because there was no Syriac Gospel until Tatian completed the
Diatessaron in the mid second century, before leaving the Christian Church to found a cult related to the Severians. This book is a harmony of the four Gospels, the first one ever written as far as we know, which is lost, but which scholars have reconstructed using commentaries written by St. Ephraim the Syrian and others, and frankly, the individual Gospels make for much better reading, which explains why, as soon as the Peshitta, the widely respected Syriac Bible was completed in the fourth century, the bishops of Syria, Mesopotamia, Persia, India, and places further afield made sure that the Diatessarons were removed and replaced by the Peshitta Bibles as quickly as possible. Before the Diatessaron, the Gospel was preached orally in what became the Church of the East (indeed St. Thomas the Apostle, who is often called “doubting Thomas” but that is a gross misreading of his life and dedication, was preaching the Gospel in Kerala when the Hindu raja became enraged and martyred him with a Javelin. The Coptic “Gospel of Thomas” has enough parallels with the Synoptic Gospels that I think that it could have started out as a written reference of the sayings of our Lord, so these could be repeated verbatim when preaching the Gospel. However there are also clear heretical interpolations, and the document is written in Coptic, whereas St. Thomas spoke Aramaic, Greek, and probably proto-Malayalam, so this is a copy of a copy, and either the Synoptic quotes were copied from one of the four Gospels, or a legitimate sayings document, and this document was edited to reflect the heterodox theology of whoever wrote the manuscript.
Lest the idea of St. Thomas preaching in India seem improbable, it should be noted that thanks to the exploits of Alexander the Great, and before him the Persian and Mesopotamian civilizations, which thrived on commerce between India and the Levant, contact between ancient Greece and India was very firmly established by the 3rd century BC, and continued after the rise of the Roman Empire, and later the Muslim world became extremely powerful by controlling trade between Europe and India, just as the Mongolians, some of whom were Buddhist, others Muslims, others adherents of the traditional Mongolian Tengrist religion, and some members of the Church of the East, before the Christians of Central Asia, Mongolia, China and Tibet were killed by the Uzbek Muslim warlord Tamerlane in the 12th century AD. As a result of the commerce between Greece and India, therehave been Jews in Kerala since 200 BC; most of them, known as the Kochin Jews, have emigrated to Israel, but their synagogue is preserved, and the most famous of the Kochin Jews in recent years is the late hairstylist Vidal Sassoon.