1 Peter 2:18
For another example, take the teaching in apostolic times that slaves should be subject to their masters. Is it not true that the Orthodox Church has abandoned this apostolic teaching?
I don't think that's really the Apostolic teaching. I think was that slaves should be obedient to their masters, which has a very different connotation from subject. "Subject" implies an affirmation of the righteousness of the relationship of slavery, whereas "obedient" simply affirms in the context of that relationship that the believing slave should bear it in obedience to his/her master, while not necessarily affirming that the existence of the relationship is rightful. It's possible that the Orthodox Church's attitude on the rightfulness of slavery has developed while not contradicting the obedience part.
New International Version (©1984)
Slaves, submit yourselves to your masters with all respect, not only to those who are good and considerate, but also to those who are harsh.
King James Bible
Servants, be subject to your masters with all fear; not only to the good and gentle, but also to the froward.
What does yur Bible say?
Οἱ οἰκέται ὑποτασσόμενοι ἐν παντὶ φόβῳ τοῖς δεσπόταις, οὐ μόνον τοῖς ἀγαθοῖς καὶ ἐπιεικέσιν ἀλλὰ καὶ τοῖς σκολιοῖς.
Some Orthodox Christians claim that the Roman Church has teachings which vary from those in apostolic times. This claim is pretty hollow when you consider the fact that the Orthodox Church has abandoned certain apostolic teachings as well. And as well, you appear to deny these apostolic teachings.
You haven't noticed that slavery has been abolished, and thus, there are no slaves to submit, if you are worried about that. Neither Christ nor the Apostles laid any obligation to keep that institution (indeed, the Church choked it: for instance, married slaves could not be sold off, lest man put asunder what God had joined).
Why not have us all wear robes, speak Greek and Aramaic, obey a pagan (and persecuting) emperor.....where do you get the idea that all things are equally important? Neither Christ nor the Apostles taught any such thing.