Complex sentence: He had originally named the painting the "Lord's Last Supper", meaning the last meal that Christ had shared with Saint Matthew which was seen as derogatory towards The Last Supper story of the Bible.
Split into simpler sentences: He had originally named the painting the "Lord's Last Supper", meaning the last meal that Christ had shared with Saint Matthew. This connotation was seen as derogatory towards The Last Supper story of the Bible.