Can Jesus' instructions for life be simplified like the "Ten Commandments" of the old testament, or must we read and re-read what he has said in the New Testament and others who later interpret what he meant. i.e. "Is there a simple how-to guide to be Christian with clear bullet points."
I don't think one can do this, for several reasons.
First, even if one could produce a simple codification of Jesus' teachings, it wouldn't follow that this is a "simple how-to guide to be a Christian". Because being a Christian isn't simply a matter of following Jesus' ethical teachings; it also involves believing things
about Jesus.
Second, we just don't know with enough certainty precisely what Jesus taught or what he meant by it. Even where scholars agree on what material in the Gospels really goes back to Jesus (and there isn't much agreement even on that), they don't agree how Jesus's teaching should in general be understood.
Third, no body of teaching, even if we know it, can reasonably be condensed in such a way. It's important to realise that just making a list of the key points of someone's teaching inevitably misses much of the teaching, because it is also important how they relate to each other. Which is the most important element of the teaching? What elements are derived from others? What are the subtle nuances? I think that even if we had transcripts of Jesus' sermons, assuming he delivered any, it would still be a mistake to try to reduce them into bulleted lists.
Perhaps i'm mistaken, but i don't believe Jesus is quoted as claiming to be God in the Gospels. John's Gospel implies this, but Jesus (or more accurately the Gospels authors) never say this specifically. Again if i'm wrong someone please correct me.
Briefly, you're probably right that Jesus makes no such claim in the Synoptics and only hints at it in John, though opinions differ regarding how much weight should be placed on the various verses. We've discussed this a number of times in these threads so follow the links on the first page if you're interested.
What are the most relevant quotations by the Church Fathers that would be applicable to diologue between Catholics and Protestants today? (In other words, what quotes would give us an idea of what the Church fathers would think about the debate today.)
Which debate?
Which dialogue? And which Catholics, and which Protestants? There is no such thing as some single debate between them. Catholics differ among themselves and Protestants differ among themselves, and there's a vast web of discussion between all of them, all the way from Reformation-style bashing of each other to the ecumenical movement and indeed people who aren't clearly in either camp (e.g. Anglo-Catholics).
Not only that, but I think that looking for particular quotations from the Church Fathers or indeed anyone else that's relevant to the issues of ecumenical dialogue is a mistake. You can't hope to understand the Fathers from isolated passages. It's essential to read their works properly, from start to finish. Only in that way can you get a sense of the real minds of the Fathers and the way that they thought. Doing that will show that, regardless of the particular positions adopted, most of the Fathers were very distant from most Protestants in spirit and much closer to Catholics, but still quite different from modern Catholicism. But even that is a huge generalisation - about the Fathers as well as about Protestants and Catholics.
How common was belief in Transubstantiation in the Early Church?
It depends on what you mean by "transubstantiation". The technical language of substance and accidents was not used by early Christians, since it is Aristotelian and they were mostly Platonists who hated Aristotle. However, the basic idea that the bread and wine are transformed into the body and blood of Christ even while they appear unchanged can be found in various patristic writers.
You can find what appears to be this idea as early as
Justin Martyr. But it seems clearer in later writers such as
Ambrose of Milan (para. 125) and
Gregory of Nyssa. It is taught quite clearly by
Cyril of Jerusalem.
I would say overall that there aren't all that many patristic passages on the subject, but when it is mentioned, rival views seem not to be discussed. I would infer from this that at least by the fourth century Christians generally believed that the bread and wine at the Eucharist were genuinely transformed into the body and blood of Christ, and certainly this was an old belief by then. One can also find good support for veneration of the Eucharist at an early date.
Ignatius of Antioch famously calls the Eucharist the "medicine of immortality".
Tertullian testifies that the bread from the Eucharist was taken home and venerated, to be tasted before eating anything else.
Are there any such thing as a Protestant denomination which totally rejects Calvinism?
I should think that the average Anglo-Catholic or high Anglican churchman would reject everything to do with Calvinism. Some of them are more Catholic than the Catholics.
When were the first "Calvinistic" viewpoints advocated (Technically the word would not have been used until Calvin, but I'm talking about the general idea of Predestination, or in other words, that people might not really have free will.)
One might argue that Augustine of Hippo could be interpreted in that way (in fact, it was just such an interpretation of Augustine that led to the Jansenist movement - the Jansenists were basically Catholics who believed that Calvinism was right about some things). But I think that would be a tendentious argument. The most obvious "proto-Calvinist" in your sense would be Gottschalk of Orbais, who was condemned in the ninth century for his belief in double predestination. Other figures at the time, notably Ratramnus of Corbie, argued that Gottschalk was right (at least to some degree).
If you were going to build a theology based on a scholar's perspective of what you feel Christianity teaches, what would it look like?
I'm afraid I don't think that that's possible either. There is no such thing as "what Christianity teaches". I've often said that I don't think there is any single doctrine - not even the existence of God - which every single person who calls themselves a Christian believes. When you study Christian history properly one of the main things you discover is that Christianity adapts itself to every culture it touches and changes dramatically, sometimes almost beyond all recognition. Any attempt to summarise the basic teaching of Christianity is invariably a reflection of one's own background and prejudices. If I were to do it, I would instinctively present a "Christian theology" emphasising social justice, liberal values, and a high-minded concern for the truth - but that would be more a reflection of my own values than a real assessment of what's really basic to Christian teaching. I'm sure something similar would be true of anyone.
Romans 13 is generally interpreted as saying that all worldly governments are ordained by God and so resisting their authority is resisting the authority of God.
However, I've also seen it argued that the passage really means the opposite: the higher powers mentioned here are The Church (or its leaders, or its doctrine, or God's commandments) which God has ordained and which must be followed. However, Worldly Governments (or at least some of them, those hostile to godliness) are not ordained by God, and are thus have no authority over us.
Which interpretation do you think is more valid?
I must say I haven't heard of the alternative interpretation that you mention, so perhaps I can't evaluate it properly. But it sounds pretty implausible to me. That is for two reasons. The first is that the plain meaning of Paul's text is surely to civil authorities, as he mentions the wielding of the sword and the paying of taxes. So to interpret it as referring to ecclesiastical authorities, there would have to be some very good reason in the text - but I see no such reason. The second is that ecclesiastical authorities of the kind that would be implied if that were the meaning of this text did not exist in Paul's day, and he does not talk about them elsewhere. E.g. 1 Corinthians 14:26-33 describes quite a democratic approach to worship. 1 Corinthians 11:18-34, on the Eucharist services, appears to envisage no-one actually in charge at all. The only place in Paul's undisputed letters where he mentions any church authorities at all is Philippians 1:1, which mentions bishops and deacons, a puzzling reference not found anywhere else in his writings (and which some think inauthentic). Therefore, for Paul suddenly to start talking about how the church authorities are ordained by God and how everyone must obey them would be wildly out of character with the picture of church organisation presupposed by his writings in general.
To add to MagisterCultuum's post, Romans 13 also refers to the government punishing those who do evil and praising those who do good. I've always interpreted this to mean that if a government doesn't even do this at a basic level (Nobody does it PERFECTLY but most governments do it to a point, a few incredibly warped governments do the opposite) they lose their legitimacy and can legitimately be overthrown or disobeyed. Does this argument hold any water in your view?
I'm afraid this doesn't reflect what the text says at all, at least as far as I can tell. There is no indication there that the legitimacy of the authorities is conditional. Paul doesn't say "Just governments are legitimate"; he doesn't even say "Governments are just, and this why they are legitimate". He says quite baldly that governments
are legitimate. See Romans 13:1:
Paul said:
Let every person be subject to the governing authorities; for there is no authority except from God, and those authorities that exist have been instituted by God.
That seems to me to be saying quite unequivocally that all governing authorities are put there by God. Compare John 1:3 on a different subject:
John said:
All things came into being through him, and without him not one thing came into being.
No-one could interpret the John passage as allowing for the existence of things that came into being without the Logos - it is absolutely explicit that there are no such things. Similarly, the parallel wording that Paul uses seems explicitly to preclude the existence of any governing authorities that are not instituted by God.
Certainly Paul then goes on to say that the governing authorities are oppressive only to the wicked and they encourage only the good. We may well question the truth of this, but I'd say that Paul's argument here shows only that Paul was rather naive when it came to the nature of government, not that he thought there were conditions for the legitimacy of government. I see nothing in the text to think otherwise.