On the contrary, they are scripture; but quoting one bit and ignoring the rest said on the subject is just over the threshold of dishonesty. These two verses show that the wine was still wine. So either he was speaking symbolically, or he was powerless. One of these two choices is not blasphemous. Can you guess which?
Many of us don't share the belief that Matthew 26:26 is contradicted by Matthew 26:29 or that Mark 14:22 is in conflict with Mark 14:25. The God who made all things is powerful enough to make the fruit of the vine also the blood of Christ. Christ told us He did so and we believe Him.
Your suggestion that believers in the literal word of Christ are dishonest is a curious evangelistic tactic. Good evening.