The Apostles were fallible and even disagreed strongly at times - it was a learning curve for them. Post resurrection does not imply perfection among them. Jesus clearly corrected them post resurrection. This is clear from Acts 24:35ff
Indeed, but collectively they were infallible and the Scripture they wrote is inspired and infallible. In the same manner we can assert the New Testament canon of St. Athanasius and the Nicene Creed (with which St. Athanasius was also involved) are infallible because the
entire church has accepted them. Likewise with the first three ecumenical councils, and with regards to their theological principles, the fourth through seventh, which were mirrored by equivalent actions from the Oriental Orthodox, so that despite the problems at Chalcedon the Oriental Orthodox and Eastern Orthodox faith is effectively identical.
More importantly, is there a "wrong" branch? Playing devil's advocate here, but there is a Biblical president of God advocating disunity; Babel. In that case too much unity resulted in people deifying themselves.
Yes, in this respect: the Orthodox (Eastern and Oriental) never experienced a Reformation, because the problems that plagued the Roman church during the 14th-16th century such as the corruption of the Avignon Papacy and the Borgias and the damage to the Vatican by the failed military campaigns of Julius II and Leo X, resulting in Rome being sacked again, and the sale of indulgences, which was correctly banned by the Council of Trent, did not happen in the Christian East. Rather, any time a schism has occurred in an Eastern church it has been because a bishop has made an ill-advised change to the liturgy, and the schism has been a traditionalist reaction.
Now, in a sense, this is what Martin Luther tried to do as well - the problem was never Luther, it was Calvin and Zwingli and Boucher, who embraced an iconoclastic theology. There were errors in Luther’s theology, but Luther thought he was reverting the church to an older state, which was the correct disposition. It was also initially the view of Cranmer, as far as we can tell, before he came under the influence of the Calvinists or Zwinglians and took more extreme measures. However, the Anglicans managed to revert these.
The real tragedy is that Lutheranism’s golden age of Lutheran Orthodoxy was prematurely brought to an end by the Prussians and other Calvinist princes seeking to dilute Lutheranism with Rationalism and crypto-Calvinistm, which combined with Pietism, did severe damage. For this reason the Continuing Anglo-Catholic Churches and other High Church Anglican churches that are conservative typically have higher Marian devotion and other desirable liturgical features than the average in many Confessional Lutheran churches - but the good news is Confessional Lutherans like yourself are working on this.
At some point High Church Anglicans, Confessional Lutherans and Traditional Latin Mass Catholics may need to set aside differences in the interest of the common Patristic heritage of each to form a united Western Orthodox church in communion with the Eastern and Oriental Orthodox, and while small, the two Western Rite Orthodox Vicarates provide two templates for this - the Antiochian Western Rite Vicarate offers a de minimus approach for implementing Patristic theology with modified Anglican and Catholic liturgies (and services based on Lutheran preferences would fit right in, particularly since Lutherans have since before the 1950s been aggressively adding features of Orthodox liturgy like the Great Litany).
ROCOR’s Western Rite Vicarate takes a more aggressive approach, attempting to recover ancient Roman worship from before the Great Schism and also in attempting to avoid any departure from the Byzantine liturgical calendar as used by ROCOR, the result being as close as you can get to pre-schism worship in Western Europe in those areas where the Roman Rite was used (there has also been some work done with the Ambrosian and Mozarabic Rites, but not as much as I would prefer; I personally prefer these, and the other Gallican liturgies, to the Roman, as I prefer the flowery style of prayers that these rites share with the Eastern liturgies, most of the time - there are times however when the concise and impactful simplicity of the Roman Rite is refreshing - if I ever join the Roman Catholic Church as a priest, which I would have done had Pope Benedict XVI not resigned, it would be because of the multi-rite faculties some priests can obtain, because I am not content with one liturgical rite; there is so much beauty and I myself use all of the ancient liturgical rites together with bits of the Anglican, Lutheran and Wesleyan* liturgical heritage to varying extent within an Orthodox theological framework.
*Specifically, the hymns of Charles Wesley, which are the finest and most doctrinally expressive chorales originally written in the English language, for example, Christ Our Lord Has Risen Today. They are evocative of those of Martin Luther, who was also theologically expressive in his hymns. This in turn aligns with the Patristic principle of hymnody - wherein the ancient hymns of the Western and Eastern church are doctrinally expansive, as compared to the vacuous praise and worship music which now predominates.
Consider the pure doctrine found in hymns like Te Deum Laudamus, Ho Monogenes, Phos HIlarion, the Trisagion, Haw Nurone and the various Canons, Kontakia, Troparia and Metrical Homilies of the East, and Antiphons, Graduals, Introits and Session Hymns of the West, and compare that to the banal rock music which is unable to convey anything substantial about the nature of the Trinity, the Incarnation, the Economy of Salvation, the relationship between God and the Theotokos, the relationship between the Apostles and the faithful, the nature of the Church, the personhood of the Holy Spirit, the actions of the Angels, et cetera.
