I doubt very seriously if kosta will get any church/Church father who would say the Old Testament has nothing to do with Christianity.
BTW-It seems to me there was a heretical group that wished to toss out the Old Testament as irrelevant. The reason the Church Fathers kept it in was simply because our Lord Jesus and the Apostles quoted extensively from it. Unfortunately I don't have time to explore this at the moment.
I never said it has nothing to do with Christianity. I just find some parts of it, shall we say, "less" Christian and even outright alien to the teaching of Christ. But, I admit my failing to understand the Bible correctly and only ask, but never claim that my doubts are correct or even justified.
Unlike Marcion, the heretic you are hinting at, I am not asking to abolish the OT; just to explain it in the light of the New. However, you are right about the Church silence (and for a good reason). There are no extensive commentaries in Orthodox sources as to why the angry vengeful God of the Old Testament is the same loving, humbling and forgiving God of the New. If there are, I would welcome them myself!
The Church (both Orthodox and Catholic) has a set repertoire of evangelical readings throughout the year. These readings repeat the same select verses from the New Testament. During this time of the Great Lent, the Old Testament readings are included. The Liturgy itself has some 40% of Old Testament material and, as you pointed out, Christ Himself and the Apostles quoted from it (95% from the koine Greek Septuagint and 5% from the Hebrew Masoretic Text), but only those verses that were relevant to Christian teachings.
At the time of Jesus walking on earth, the Hebrew canon was not set, so who was to say what was Scripture? Obviously, those parts which +Paul excised for the Gentiles regarding the observance of the Law are not binding and Christians are not required to believe or obey them. If so, are they rituals or are they part of worship as God wanted it? Then, why not cut out the Law?
Tonight, on Holy Wednesday morning prayers, there were verses about sacrificing animals. How does that fit into our Christian practice of worshiping God?
So, then the verse "All scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness" [2 Tim 3;16], raises the question just what is Scripture. Or can we assume that what was necessary for the Christian faith was quoted in the New Testament; nothing less or more.
The position of the Church on issues that may be more difficult is silence. The belief is that if Christ believed in the Old Testament by quoting from it, then it must be true, even if we can't understand it or see it that way. In other words, it is a mystery (your favorite HD).
The Orthodox Church takes the same stance with the Revelation of John. It it the one book that took the longest for the Church to accept as Scripture. The Orthodox Church never quotes from it or reads from it in the New Testament readings.
But, I would welcome if someone would direct me to a source that will answer all my questions about the OT in light of the New Testament. That would imply, in case you wonder, that there is a mortal human being who understands Scripture perfectly. But, if the OT says that Job was a perfect man [Job 1:1], I am optimistic. :)
Anyone willing to volunteer?