Mr Lucas complains that Holloway, while Bishop of Edinburgh, abused his position by helping the media present orthodox Christian faith as extreme and outdated. If indeed the bishop did that he is to be praised, not condemned.
It is people such as Mr Lucas who, presumably, regards himself as a faithful Christian, along with the vast majority of clergymen who insist on the inerrancy and literal truth of the Bible, who are the root of the Church's demise.
They may believe, literally, that God sent his son to a slow and agonising death on the cross to atone for mankind's sins or that Christ supernaturally rose from the dead and ascended to heaven, but there are growing numbers of modern-thinking Christians who find such notions repugnant and incredible.
This does make them any less faithful than Mr Lucas; it merely indicates their worldview is different from their ancestors of 2,000 years ago. Until more clergymen slacken their grip on the past and start presenting Christianity in a more modern and relevant context, the Church will continue its decline.
Agnosticism is a broader church than some of your correspondents may want to admit. Some people may use the term simply to mean that they do not know whether religion is true or not: they may appreciate the arguments on both sides and feel unable to reach a personal conclusion. We could call this weak agnosticism.
Others may go further and deny the very possibility of knowing whether religion is true - it is not just unknown by them personally but unknowable in principle. We could call this strong agnosticism.
Even some religious believers may call themselves agnostics, relying on faith or belief rather than knowledge. A famous 14th century work of Christian mysticism is called The Cloud of Unknowing. More recently, the Scottish philosopher RM Hepburn described himself as a person of religious temperament beset by intellectual difficulties, an agnostic position with which many would identify.
Richard Holloway's point (Books, 18 December) about "religious illiteracy" was brought home by a conversation I had with a ten-year-old boy. He startled me by saying he'd be glad when Christmas was over as he hated Jesus and just wanted to spend the money he was hoping to get as a present.
When I asked him why he hated Jesus, he said something fairly incoherent about all religions being rubbish but then added that if he was religious himself he would be a Protestant, "because Protestants are against Christianity". No amount of persuading on my part would convince him that Protestants are Christians.