Calling Matthew, Mark, Luke, and John the "orthodox gospels" is more anachronism from you in your attempt to make a theological point. There was no orthodoxy in the 1st or 2nd centuries.
Right! And this is exactly why today's "Bible believing" Christians (ie. Biblical literalists/ fundamentalists) have no leg to stand on when they say they are returning to the "fundamentals" of Christianity-- and especially when they insult the traditional teachings of Catholicism/ Orthodoxy. They fail to see that
the Bible that they quote as their source of absolute truth
IS, precisely, the product of Catholic/ Orthodox tradition. It simply would not exist in anything like the form it does except for Catholic/ Orthodox tradition. (Hence, my statement, the Bible is a Catholic book.) "Bible believing" fundamentalists/ literalists are the ones whose entire world view is based on anachronism. The doctrines they believe (full humanity and divinity, Trinity, virgin birth, etc.) and the document based on which they believe them (the Bible) simply cannot be divorced from the historical processes and traditions that created them.
Just about the only doctrine that Biblical fundamentalists believe that
isn't a product of Catholic tradition is sola scriptura-- which ironically, is found nowhere in the Bible, and which the earliest Christians
certainly did not believe (how can you believe in "Scripture alone" before there
is "Scripture," lol).
There is also the reality that many of the earliest Christian fathers, such as Origen, were anything but scriptural literalists and introduced symbolic interpretations of
many passages, but that is another point.
You're right that the hypostatoc union and the trinity aren't taught in scripture, at least not clearly. Even if they're true though, many Catholic teachings are false, so I don't see what point you're trying to make with these strawmen. Even if the hypostatic union and trinity are true, this doesn't mean the RCC's claims about apostolic succession are true. A broken clock is right twice a day. To call the conclusions reached at church councils "authoritative" is to beg the question.
Well, who are you (or who is any 18-21th century person) to say that finding X of early Church tradition is authoritative and true, but finding Y is not? The passages that point to apostolic succession and the Real Presence of Christ in the Eucharist are, in fact,
more clear, less ambiguous, and less internally contradicted than some of the passages that point to Jesus' full humanity and full divinity and the Trinity, for example. The idea that you, a person in the 21st century, using your Bible-- which is, once again
a product of Catholic/ Orthodox tradition-- can get closer to the "original" spirit of Christianity than the early Church fathers living in the second and third centuries is nothing but ignorance. At best...