Floo
I don't think Spud is arguing for a 'literal' truth in these instances (at least as far as dating the Last Judgment, End times etc). What he's doing is promoting an extremely convoluted interpretation of a number of scriptures. If he were arguing for a literal truth on these matters, then there wouldn't be such a devious distortion of the meaning of such words as "soon", "quickly", in "this generation" etc. We all know what the literal meanings of such words are (and many modern biblical scholars of a critical outlook are quite happy with such literal interpretations here). The reason why fundamentalists and evangelicals are not happy with a literal interpretation of the time-interval involved is that it leads to the horrific implication that Jesus got it wrong.
This fits in with the usual procedure of fundamentalists and evangelicals: unless the scriptures are obviously of a poetic nature such as Psalms and Song of Solomon, they are quite happy to proceed "literally". This brings problems, because contradictions and other anomalies soon arise, and there are many - as you well know. It is then that the whole apparatus of convoluted exegesis and interpretation comes in to play, until the obstacle is explained away, and then the literal reading can continue until the next stumbling block.
So while such Christians certainly believe that all the Bible is true , it's certainly not the case that it's all a literal truth that's being asserted.
You need to look at the bigger picture. From the beginning, God promised that he would send a Messiah to save mankind from sin and death. Until that time, he set up the sun, moon and stars as signs that told men about God and when to worship him. Passover was celebrated at the first full moon after the vernal equinox, for example.
When the Messiah came and fulfilled the Passover and other festivals by his work of salvation, the whole system became obsolete. Jesus gave the Jews "The sign of Jonah". This was the death and resurrection of the prophet, followed by 40 days during which they had to repent to avoid destruction. This was a sign to Israel that after the death and resurrection of the Messiah, there would be 40 years for them to repent and start relying on Jesus rather than the temple sacrifices. But they continued to use the temple for sacrifices even though that system was obsolete. The sacrificial system fulfilled, it was destroyed completely in AD 70. This is prophesied in Joel 2:31, pictured as the sun and moon being eclipsed, because they were the 'clock' that the system relied on.
As the gospel of the Messiah's salvation was preached to the nations, all their systems of belief would be replaced by the 'sun' of Christ, and Christianity the true religion. This is described in Joel 3:15 as the sun and moon being darkened for the Gentiles. It is what Matthew 24:29-31 is about. The sign would appear of the Son of Man in heaven: in other words, people would understand that Jesus is king, because they would see the tribulation of the saints and God's judgment in response (typified by the persecution of the Apostolic Church under Nero and the events of AD 70 that followed).
Matthew 23-25 is a structural unit, which begins with the scribes and Pharisees on the judgment seat (of Moses) and ends with Christ on the throne at the last judgment.
In ch. 23-24 he basically says that the sin committed during the time leading up to the Messiah would come upon that generation. And he finishes in ch 25 by giving the eternal destiny of the righteous and the wicked.
The thing is that the judgment on the generation that rejected the Messiah is conflated with the final judgment that includes the generations to whom the gospel has been preached (see Mat 28:19). What we have is a situation a bit like the Old Testament prophets gave. When Nathan told David that David's son's kingdom would last forever, that was pointing not just to Solomon but to the future Messiah. When Isaiah told Ahaz that a virgin would have a son who would be called Immanuel, that was fulfilled both in (?) Isaiah's wife's son and in the Messiah.
Likewise, the prophecy of the destruction of the wicked in the generation that rejected the Messiah (Mat 23:35) points also to the final judgment at the end of the gospel age. The two are separated in Revelation, where we are shown the destruction of the great city (Babylon, symbolizing Jerusalem, Rev. 17-19), followed by the thousand years during which Satan cannot deceive the nations because the Church binds him with its preaching of the gospel of salvation (Rev 20). Then we are shown the last judgment. There is a double fulfillment.