Personally, I think it'd be more productive to search for a conceptually simpler, more primitive "Christianity" rather than seek to find a synthesis between Lutheranism, Orthodoxy and Roman Catholicsim.
That sounds nice, superficially, but such an ideal church suffers from the not inconsiderable problem that it doesn’t actually exist. The One Holy Catholic and Apostolic Church still exists, but a series of unfortunate schisms have resulted in division, so you have the four ancient churches (Roman Catholic, Eastern Orthodox, Oriental Orthodox and the Church of the East), some minor schisms from the Eastern churches (almost entirely in protest of ill-advised changes to the liturgy; these chiefly include the Russian Old Believers and the Greek, Romanian and other Old Calendarists), and resulting from a period of severe corruption in the Roman church lasting from the Great Schism until the admirable Counter Reformation under Pope Pius V, which started to become progressively worse in the late 13th century with the dreaded Inquisition and subsequently, the decadence of the Avignon Papacy and the Borgias, we saw the emergence of the Magisterial Protestants such as Luther, Cranmer and Calvin.
Of these three, the Lutherans and Anglicans in particular, as well as the Anglican-descended Methodists, and the liturgical Presbyterian adherents of what is known as Mercersburg Theology, who are sometimes called Scoto-Catholics, have done an admirable job, in my opinion, preserving the Apostolic faith. Interestingly, two of the earliest reformers, St. Jan Hus and St. Jerome of Prague, who desired a restoration of vernacular liturgy and communion in both kinds, which had been lost when Austria conquered the Czech lands, and imposed the Roman Rite*, were the original founders of the second oldest Protestant denomination**, and the oldest non-Calvinist Protestant denomination, the Moravians, and are also venerated as saints in the Eastern Orthodox Church of the Czech Lands and Slovakia.
So, basically any of the churches whose members identify with the spirit of the Traditional Theology represent the authentic, ancient spirit of Christianity, albeit with one caveat - the Novus Ordo Missae that predominates in the Roman Catholic Church, and which is at risk of becoming even more predominant owing to Pope Francis effectively reversing the best of Pope Benedict XVI’s achievements,
Summorum Pontificum, and abolishing the Pontifical Commission
Ecclesia Dei created by Pope John Paul II (whose sainthood along with that of Pius X I increasingly feel is justified, unlike that of Popes John XXIII and Paul VI), which was created to provide Roman Catholics with access to the traditional Latin Mass, in response to the rapid growth of the SSPX in the 1980s, is not usually a traditional worship experience, unless it is celebrated in a very specific way which is extremely rare (ad orientem - that is, the priest facing the altar together with the congregation where possible, with traditional music as instructed by St. Pius X , in a document still in force but which most dioceses and parishes in the US seem simply to ignore, traditional vestments, and the avoidance of Lay Eucharistic Ministers amidst other innovations.
That still leaves the three year lectionary, which is unprecedented in the history of Christianity (the Jerusalem Talmud, dating from the 8th or 9th century
anno domini, featured a three year lectionary of Torah portions and corresponding Haftarah (lessons from other books in the Old Testament, or Tanakh), but this never caught on outside of Palestine, and today, the Babylonian Talmud with its one year lectionary is predominant even in Jerusalem (the evidence I have seen suggests the one year lectionary is closer to the original lectionary implemented in the Temple and the Synagogues by St. Esdras (Ezra) the High Priest under St. Nehemiah the Prophet, and its Torah and corresponding Haftarah lessons can still be found in the lectionary of the Assyrian Church of the East, albeit reorganized to correspond with the Gospel and epistle lessons).
The same caveat regarding the Novus Ordo Missae also applies in large measure to Protestant liturgies revised after the Novus Ordo, which adopted its various features, like celebration versus populum (the pastor facing the congregation during Holy Communion), the three year Revised Common Lectionary, derived from the Novus Ordo Missae, the blaring modern praise and worship music, and other deformations. This does not apply to all recent service books in equal measure: the 1979 Book of Common Prayer can be served in a very traditional manner using Rite I or the traditional language variant, the Anglican Service Book (the use of that book, and other traditional language adaptations of the contemporary language parts of the book are expressly authorized by a rubric, and all of the existing BCP editions published by the Episcopal Church were released at the time of their release into the public domain - note this does not apply to the 2019 BCP issued by the ACNA, which I am not a fan of; the 2006 Lutheran Service Book is also very good.
If you really want an experience of church from antiquity, the least modified liturgical rites are the Mozarabic and the older form of the Carthusian Rite, but the former requires travel to Toledo, in Spain, not Ohio, and the latter requires a very difficult to obtain pilgrimage to a Carthusian chapterhouse (the Carthusian term for monastery), which is only offered in the context of discerning suitability for service as a lay brother or choir monk, and more specifically, one of the small number of chapterhouses still using the old rite. After that, the most ancient readily accessible liturgies are those of the Aramaic-using East Syriac Rite (used in the Assyrian Church of the East, Ancient Church of the East, the Chaldean Catholic Church, and the Syro Malabar Catholic Church), the Coptic Rite (used in the Coptic Orthodox and Coptic Catholic churches), the Aramaic-using West Syriac Rite, particularly as used by those Syriac Orthodox Churches in the Middle East (as the St. Thomas Christians in India historically used the East Syriac Rite until the 18th century), the Ethiopian Rite, as used in the Ethiopian Tewahedo Orthodox Church and the Eritrean Tewahedo Orthodox Church, and the Russian Old Rite (with priests; there is a ROCOR parish in Erie, Pennsylvania, the Church of the Nativity, which serves the traditional Russian liturgy.
After that, the traditional Byzantine Rite as found in Orthodox and Eastern Catholic Churches (the Georgian, Greek, Albanian, and some Bulgarian, Romanian, Serbian and Antiochian parishes have the oldest music, in the form of Georgian polyphony and Byzantine chant; I myself greatly prefer Georgian polyphony, and the newer polyphonic music in four part harmony that is now dominant in the Russian and Ukrainian churches, and which is also commonly heard elsewhere, even in the Greek churches thanks to the exquisite liturgical compositions of Tikey Zes and Michaelides, but Byzantine Chant, like Gregorian Chant, is older, although Georgian three part polyphony is equally ancient). The Ruthenian Greek Catholics and the Carpatho-Rusyn Orthodox (sometimes called Russian Greek Orthodox Churches in the Orthodox Church of America; other parishes are in the American Carpatho-Rusyn Orthodox Diocese under the Greek Orthodox Church) has a beautiful system of congregational singing called Prostopinije, which along with Russian Znamenny Chant, found in Russian Old Rite and Old Believer churches like the aforementioned Church of the Nativity in Erie, PA, are perhaps the oldest surviving systems of congregational singing.
Then there is the traditional Latin Mass and variations thereof, the most common being the Tridentine Mass, but there is also the Dominican mass, and several other variations specific to particular cities and religious orders, such as the Rites of Lyons and Braga, and the Carmelite, Norbertine and the aforementioned Dominican and Carthusian Rites. There is also the Ambrosian Rite, related to the Mozarabic Rite, but whereas the latter is only regularly served in a small side chapel in Toledo’s cathedral, the former is the predominant liturgy in the entire region of Milan, and features incredibly beautiful music, vestments and liturgical pageantry, especially the astonishing Rito di Nivola on the Feast of the Elevation of the Cross (September 14) in which some ministers and clergy ascend in a cloud-shaped gondola of Baroque (or perhaps Rococco) provenance to the reliquary high in the ceiling where one of the largest and most valuable fragments of the Holy Cross is kept.
For those who would scoff at liturgical pageantry, I would encourage them to read a history of the majestic worship in Constantinople before the Turks conquered it, and look at the ancient and beautiful worship surrounding Good Friday and Easter Sunday at the Holy Sepulchre in Jerusalem, especially the Orthodox services, and likewise the Great Blessing of Waters in the River Jordan on the feast of the Baptism of our Lord (Epiphany, however, all Orthodox services in the Holy Land follow the Julian calendar, so this works out to be January 18th).
*after the subsequent Union of Brest-Litovsk and the Counter Reformation, this would not have happened, in that the Roman Catholic Church under the good leadership of bishops like Pope Pius V and Carlos Borromeo the bishop of Milan ceased to impose changes in liturgical rite, and instead developed the Eastern Catholic Churches, and by 1911 a full equivalence of rite was at least in theory and in the view of Pope Pius X the official position; one of the few good things to come out of Vatican II in my opinion was that this was finally delivered on, and the various changes to the Eastern Rite liturgies, which most liturgical scholars call Latinizations, but which I prefer to call Romanizations, as they represented the imposition of practices specifically from the Roman Rite, and were also applied to other Western Latin liturgical rites, like the Ambrosian Rite and the Dominican Rite, were mostly removed from the various Eastern Catholic liturgical rites, although unfortunately not from the other Western rites; indeed the Dominican Rite came very close to disappearing and there was a time when the Carmelite Rite was disused, and in Portugal, the traditional Rite of Braga is seriously endangered.
** The oldest Protestant denomination is the Vaudois, or Waldensians, which started as a group of unsanctioned friars similiar to the Lollards of England, around the same time, but they were much more successful, organizing into a church in Southeast France. In the 16th century, following the horrifying massacre of 15,000 Vaudois men, women and children in Piedmont, through which they had been promised safe passage, the surviving Vaudois settled in Switzerland and embraced Reformed Calvinist theology, and there is at least one Waldensian parish in the Presbyterian Church, USA. In Europe, the Vaudois returned to Italy and recently merged with the Methodists to create the largest Protestant church in Italy. However, anyone hoping for a primitive Protestant church is in for a disappointment, as the Waldensians are essentially a Reformed church along Continental European lines, which also now embraces Methodist as well as Calvinist positions, much like the United Church of Canada or the Uniting Church in Australia.