What do you think about C.S. Lewis' "Lord, Liar or Lunatic" argument?

"A man who was merely a man and said the sort of things Jesus said would not be a great moral teacher. He would either be a lunatic — on the level with the man who says he is a poached egg — or else he would be the Devil of Hell. You must make your choice. Either this man was, and is, the Son of God, or else a madman or something worse."

The main issue I have with this argument is that it isn't reasonable to just assume that Jesus really did say all the statements attributed to him in the gospels. Here's an example that I think perfectly captures why it doesn't make sense to just treat all the "red letter text" with the presumption of accuracy. This example isn't about Jesus claiming equality with God, but I think it does still relate to this issue pretty well.

In John 2:18-19, skeptical Jews ask Jesus for a sign of his divine authority, and Jesus responds, "Destroy this temple, and in three days I will raise it up." This is presented as a prophecy of his death and resurrection. Such a prophecy coming true could certainly be interpreted as vindication of a claim to divine authority.

However, in previous gospels (Mark 14:57-58 and Matthew 26:59-61), ones that practically all Biblical historians agree were written before the gospel of John, there is a different version of this claim about destroying the temple. In those gospels, it's other people testifying in Jesus' trial that he said it, and they are explicitly referred to as false witnesses. If those verses in John were things Jesus really said, how could those witnesses be giving false testimony?

That's just one of many examples that the gospels show clear signs of developing legend, of a fish story that grows and magnifies over time. And though there are some verses in Mark that can be interpreted as indicating that Jesus is the Son of God, most of the key verses that people quote to defend his status as deity come from John (the latest gospel).

If we can't trust that a statement ascribed to Jesus in the gospels was actually said by the real historical Jesus, then we don't really have any idea whether he claimed to have divine authority or not. But even beyond that, there's one further point to consider; Jesus never explicitly claimed to be God in so many words (even if we do accept his sayings in the gospels as completely accurate). He just claimed things that Trinitarian Christians interpret as being things only God could claim. But if God really is the ultimate authority, I see no reason that he couldn't confer onto a purely-human Jesus the authority to forgive sins or things like that. If Jesus was essentially God's representative on earth for that time and culture, then I don't see any reason why he couldn't be the bearer of that authority without actually being the same being as God the Father.

So, basically, there are two key assumptions Lewis makes which undercut his argument. 1) That the sayings attributed to Jesus in the Gospels are accurate, and 2) that those things could only rightly be said by someone who is the Son of God. If either one of these assumptions are not true, then the argument falls apart (and that's without even considering the common flaw of all trilemmas, that there might be more options that we just haven't think of).