that of origin, meaning of life, morality, and destiny. He said that while every major religion makes exclusive claims about truth, the Christian faith is unique in its ability to answer all four of these questions. He routinely spoke on the coherence of the Christian worldview, saying that Christianity is capable of withstanding the toughest philosophical attacks. Zacharias believed that the apologist must argue from three levels: from logic to make it tenable; from feelings to make it liveable; and from whether one has the right to use it to make moral judgments. Zacharias' style of apologetics focused predominantly on Christianity's answers to life's great existential questions with defense of God. He argued that the dominance of the visual in modern communication systems has impacted people's capacity for abstract reasoning altering their way of perceiving things; however, the integration of abstract reasoning into one's worldview is important to have its base grounded in absolutes rather than on relative feelings and fads. Academic credential controversies In an earlier edition of his biography and in other literature, Zacharias claimed to have studied at the University of Cambridge and was a visiting professor at the University of Oxford. In multiple speaking engagements he said that he had taken a class in quantum mechanics under John Polkinghorne and while a visiting scholar at Cambridge had heard Stephen Hawking lecture, seeing him struggle between agnosticism and theism. Zacharias often claimed in books and sermons that he was invited to be a visiting scholar at Cambridge, where he focused his studies on Romantic writers and moralist philosophers. The veracity of Zacharias's purported academic positions at the universities of Oxford and Cambridge was questioned. Christian academic Warren Throckmorton stated that Zacharias "wasn't being truthful" in his claims, pointing out that he had been a visiting scholar at Ridley Hall, a theology school in the city of Cambridge which is unaffiliated with the university. Atheist commentator Steve Baughman also ran a website exposing how Zacharias exaggerated his qualifications. In 2017, Christianity Today reported accusations that Zacharias had exaggerated his academic credentials; for instance that he had referred to himself in multiple articles and videos with the title "Doctor" or "Dr.", despite lacking a PhD qualification. In response, Zacharias said he had been "conferred ten honorary doctorates" and said further that "in Ravi's homeland of India… honorific titles are customary and are used frequently out of respect for elders,