That line of reasoning always gets me. The fact is, Jesus and his apostles did not advocate or follow the plain, literal interpretation of Scripture.
The Pharisees studied the Scriptures intensely, yet they entirely misunderstood the mission and message of Jesus. Why? Were they unable to understand the Hebrew Scriptures, written in the same "plain words" that today's Christians also read? If you look closely at the gospels, it's easy to understand why the Pharisees rejected Jesus as Messiah: They focused only on those prophecies of a Davidic King, which they took literally. They did not recognize John the Baptist because they were expecting a literal Elijah. They did not recognize the Christ because they were expecting a literal, political deliverance from their literal, political enemies. Jesus did not literally sit on David's throne and rule forever. By the Pharisees strictly literal reading of the prophets, Jesus could not be the Christ.
Second, we should ask ourselves: What was the hermeneutic of Jesus? Was it a literal, plain reading, or something else? If we follow the storyline of the gospels, Jesus is constantly upbraiding his disciples for failing to understand. And what is the common thread of their misunderstandings? Without fail, the situations when the disciples and the crowds misunderstand Jesus occur when they take him literally and, thus, miss his greater meaning, which is metaphorical. Examples:
Then Jesus said to them, “Don’t you understand this parable? How then will you understand any parable?" (Mark 4:13)
“Every plant that my heavenly Father has not planted will be pulled up by the roots. Leave them; they are blind guides. If the blind lead the blind, both will fall into a pit.” Peter said, “Explain the parable to us.” “Are you still so dull?” Jesus asked them. (Matt. 15:13-16)
“Be careful,” Jesus said to them. “Be on your guard against the yeast of the Pharisees and Sadducees.” They discussed this among themselves and said, “It is because we didn’t bring any bread.” Aware of their discussion, Jesus asked, “You of little faith, why are you talking among yourselves about having no bread? Do you still not understand? ... How is it you don’t understand that I was not talking to you about bread?" (Matt. 16:6-11).
Virtually all of Jesus' teaching relies on symbolism and metaphor, and he constantly upbraids his disciples for their slowness to understand his metaphors, yet his present-day disciples insist we should follow in the footsteps of the Pharisees and adopt a literal reading. Isaiah's words are still true:
He said, “Go and tell this people:
“‘Be ever hearing, but never understanding;
be ever seeing, but never perceiving.’