I believe the root of his position lies in this statement:
He wrote: “[I have] immerse[d] myself in contemporary Biblical scholarship at such places as Union Theological Seminary in New York City, Yale Divinity School, Harvard Divinity School and the storied universities in Edinburgh, Oxford and Cambridge.”[2]
Union Theological Seminary became a well spring for liberalism, secular humanism, social gospel, and supportive of leftist/communist causes beginning in the 1950s. It is from here that many of his ‘beliefs’ probably came and that he has spread over the decades.
By what he has preached, I believe that he decided that his goal in life was not preaching the Gospel of Jesus, but the destruction of Christianity.
I agree. I think every one of those seminaries you mentioned at one time stood for the orthodox Christian faith but that stand was slowly whittled away into the institutions they now are where anything goes - all in the name of education and progress.