howdy Fish,
welcome to the forum. I am going to take a different approach then the rest of the posters here - one that avoids the actual Flood debate. (Being such an obviously fascinating and important subject you can find a ton of info on the Net regarding that topic.)
My approach concentrates instead on how we should view "references" and allusions by persons in the Bible.
Very simply, when someone, for example Jesus, refers to another person he may be citing (accepted) history, he may be citing legend or recalling myth, he may simply be telling a story with a moral dimension (a parable) or point to it.
So my first question I would like to ask you why you say that "Jesus seems to have believed" in the Noachian flood?
Perhaps you had in mind this passage:
(Matthew 24:36-42) 36 "Concerning that day and hour nobody knows, neither the angels of the heavens nor the Son, but only the Father. 37 For just as the days of Noah were, so the presence of the Son of man will be. 38 For as they were in those days before the flood, eating and drinking, men marrying and women being given in marriage, until the day that Noah entered into the ark; 39 and they took no note until the flood came and swept them all away, so the presence of the Son of man will be. 40 Then two men will be in the field: one will be taken along and the other be abandoned; 41 two women will be grinding at the hand mill: one will be taken along and the other be abandoned. 42 Keep on the watch, therefore, because YOU do not know on what day YOUR Lord is coming.
JWs (and maybe other Christians) understand that Jesus is here indicating a real belief in Noah and historical facts. However, as you an see, there is an alternate understanding and that is arrived at by simply asking why was Jesus referring to Noah in the first place?
Was it to indicate his belief in Noah? No. Was it to prove that Noah existed? No.
In fact Jesus is making a point about urgency and about not being caught up in the affairs of daily life to the extent that we (or rather his audience at the time) fail to appreciate the warning signs of the impending critical times (or destruction). [As the traditional explanation goes.]
But now comes the second question, would his point be just as effective and clear to his audience if the story of Noah were commonly known by his audience? The answer to that question is yes.
The audience understood that Jesus was making the above point about urgency and focus and not saying anything factually about Noah himself.
The example I usually give to people when I am discussing this point is that of the Good Samaritan.
If I tell you or anyone today, that they should help their neighbor like the Good Samaritan, if my audience/receiver knows the story (and they usually do) then they get the point. Now if I am quoted by a newspaper article referring to the Good Samaritan and it is 2000 or so years later after the story was originally told by Jesus is anyone going to believe that this means that I actually believe that there was an actual Good Samaritan as the story was told by Jesus.
I think few would believe that. And what would be the facts? Was there an actual Good Samaritan? Maybe, but most probably not. Jesus seems to have been obviously illustrating a point about who is our neighbor.
And incidently, this same situation can be applied to stories which we know either to be legends or even to known fabrications. "Hey kid, tell the truth like Washington did about chopping down the apple tree," etc.
So the point is this. The Noachian Flood was a very well known story of the Jewish heritage and history. Probably few Jews actually believed that the story was true. But because it was so well-known Jesus could make a reference to it, in order to drive home the point he was making.
However, for us today, looking at this passage and others like it in the bible we must understand that when he or the apostles or anyone, simply reference such stories it does not indicate in any way that they or their audience actually accepted the underlying facts or the truth of what is referenced as fact.
-Eduardo
