TRADITION VS SCHOLARSHIP
The answer
About a fifth. Ehrman and Méndez count 21 percent of Mark's contents that Luke leaves out. Luke also moves some of what he keeps, such as the mustard seed, from Mark's chapter 4 to his own chapter 13 (Mark 4:30-32; Luke 13:18-19).
Why it’s interesting
Scholars who say Luke read Matthew use this. If Luke handled Mark so freely, they argue, he could have handled Matthew freely too. Counts vary with how they are made, so other introductions give other figures.
Genuinely debated
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