So, if I’m understanding you correctly, all historical records of events, handed on to succeeding generations, can be called myth…
No. A traditional myth, according to to its technical definition as a particular kind of speech or writing, is a traditional story used to teach a religious truth. A traditional story is one that is repeated from generation to generation. The definition can be enlarged to include philosophical truths important within a culture in addition to strictly religious truths.
This is as opposed to the non-technical, popular definition of myth as an untrue or unproven story. (That is the sense that the word myth is used in the TV show
Mythbusters.)
Historical records can be considered myths if they are handed down from generation to generation for the purpose of teaching religious (or philosophical/cultural) truth, but records not traditionally handed down for this purpose would not be considered myths.
…In other words, when history books record that Obama was elected in 2008 on a platform that promised liberalization of abortion restrictions, can those historical records be referred to as “myth”…
Maybe. If stories about this are told again and again as a warning to future generations to be on guard so that such evils never be allowed to happen again.
A situation like that exists today within Jewish cultures, where stories of the Holocaust are told again and again so that those who suffered under the Nazis might not be forgotten and that “Never Again” would such terrible thing ever be allowed to occur. As these stories have been repeated for multiple generations now, they can be considered to have reached the status of myth.
But just the fact that an event is recorded in a history book would not be sufficient to qualify as myth.
…Or are they myth only when they are used at some later time in human history as a means to show the final stages of devaluation of human life in the womb by a majority of U.S. citizens (that is, to communicate a cultural truth of that historical period)…
That could be considered myth. The longer a story is handed on, teaching truth from generation to generation, the more firmly it may be considered to have achieved the status of myth.
…Honestly, I am not asking this to be argumentative - I really want to know. Are the words “myth” and “historical fact” to be taken as synonymous?..
No. The terms may overlap or they may not. A historical fact that is handed on traditionally to teach religious (or philosophical/cultural) truth may be considered mythic. A fictional story that is handed on the same way to teach the same truth is equally as mythic. A historical fact or a fictional story that is not traditionally handed to teach such a truth would not be considered mythic.
…Assuming all the events recorded in Scripture involving Abraham literally happened as recorded, why would they be called “myth”?..
Yes, because they have been in the past and still are today traditionally retold to teach religious truths from generation to generation.
…Are there any events in Scripture that would not be called “myth”? Why?..
That’s a very good question! A strong case could be made that as the word of God, every event recorded in the Scriptures teaches religious truth, And as the whole of the Scriptures has been traditionally handed down to teach every generation since its inception, then the whole of the Scriptures may be considered to be myth.
On the other hand, it is not unreasonable to recognize that some events in the Scriptures signify greater religious truths than other events. I think most Christians would agree that the accounts of Christ’s Resurrection, for example, represent a greater religious truth than all the various genealogies and censuses in the Old Testament. Because of this, Christians might also be expected to retell the Resurrection story more often than the census stories. So the Christian might consider the Resurrection stories to be more mythic than the censuses.
But on the other other hand (to paraphrase Tevye) a Jew might consider those genealogies and censuses to be very religiously and culturally significant because those people are his own ancestors. So it is very important to take culture into consideration when deciding what is myth.
…(How would you like to have me for a whole year in a classroom?

)
I think I would have enjoyed that.