Marcus J. Borg, a scholar who popularized a liberal intellectual approach to Christianity with his lectures and books about Jesus as a historical figure, died on Wednesday at his home in Powell Butte, Ore. He was 72. His publisher, HarperOne, said the cause was idiopathic pulmonary fibrosis. Professor Borg was among a group of scholars, known as the Jesus Seminar, who set off an uproar with its very public efforts to discern collectively which of Jesus’ acts and utterances could be confirmed as historically true, and which were probably myths.