To be honest I don't see what's wrong with his answer - I think he's quite right. He's not avoiding the question, he's explaining it. You can't just say that the Gospels are propaganda because they were written with an agenda - that's to pack a huge amount of assumptions and implications into a few words. It is anachronistic to apply modern terminology and assumptions to ancient texts and events, and you do need to explain what you mean carefully, and if anyone were to ask me the question you asked him I'd probably say much the same (although my spelling's better, naturally!). You can't conclude that a refusal to give a straight "yes" or "no" answer is unbearable vagueness - perhaps the question is so over-simplistic that only a complex answer can address it. Your question has something of the "Have you stopped beating your wife?" about it.
Now when you asked about the waffliness of modern theologians I thought you meant the dogmatic variety, and I'd stand by that. But I don't think this is true of historical theology, any more than it is true of other forms of "history of ideas" (to use a horrible phrase) or indeed history in general.
By the way, I'm not sure why you think the Gospels were written centuries apart. The earliest Gospel was probably Mark, which was probably written in the late 60s of the first century (or maybe the early 70s), and the latest was probably John, probably written in the mid-90s of the first century. So in fact, from the earliest to latest was probably only about thirty years. But I don't see why the date of the Gospels is relevant to their genre, which seems to be implied by your claim that because they were not written at the time of the events they describe, they must be "propaganda". Finally, of course, it's not obvious at all that the Gospels were written to spread the faith, because that assumes that they were intended to be read by non-Christians; I think it much more likely that they were written for internal consumption, as it were.
Also, there's no such place as "Oxbridge"!
Now when you asked about the waffliness of modern theologians I thought you meant the dogmatic variety, and I'd stand by that. But I don't think this is true of historical theology, any more than it is true of other forms of "history of ideas" (to use a horrible phrase) or indeed history in general.
By the way, I'm not sure why you think the Gospels were written centuries apart. The earliest Gospel was probably Mark, which was probably written in the late 60s of the first century (or maybe the early 70s), and the latest was probably John, probably written in the mid-90s of the first century. So in fact, from the earliest to latest was probably only about thirty years. But I don't see why the date of the Gospels is relevant to their genre, which seems to be implied by your claim that because they were not written at the time of the events they describe, they must be "propaganda". Finally, of course, it's not obvious at all that the Gospels were written to spread the faith, because that assumes that they were intended to be read by non-Christians; I think it much more likely that they were written for internal consumption, as it were.
Also, there's no such place as "Oxbridge"!