In his preface Nicholas Everitt describes how this book began life as an attempt to produce a non-partisan account of the philosophy of religion for a lay audience. As his book evolved it became increasingly partisan and he abandoned the intention to aim the book at those who had not studied philosophy before. Instead he decided to target it at third year undergraduates and postgraduates.
So before I had even reached the first page, my heart had sunk and I anticipated finding this book well beyond my abilities. However it is such a well written book that, much to my amazement, I found that I could generally follow the arguments.
The first nine chapters are essentially devoted to the arguments which theists have put forward to prove the existence of God. Nicholas Everitt considers all of these in what he considers to be their strongest form and all of them are found to be wanting.
In some respects, the tenth chapter struck me as quite pivotal. It considers 'Prudential Arguments.' The author concludes that there can be consequences of belief which would justify a believer retaining their beliefs or even give reasons for someone to adopt beliefs. Of course this has no bearing on whether the beliefs are true or not and most people do not just want to believe for pragmatic purposes - they feel the need for their beliefs to be true. This approach would put the believer in a potentially awkward situation where they would need to isolate themselves from any arguments which could threaten their beliefs.
The later chapters advance the arguments which atheists have put forward for the non-existence of God. The counter-arguments are also considered. The attributes which are normally ascribed to God are shown to be either individually self-contradictory or that they cannot be reconciled with other qualities. As the author says, 'It thus follows that not only does God not exist, he cannot exist. For ignorant agnostics who unthinkingly proclaim that it is impossible to prove or disprove the existence of God, here is a putative set of disproofs.'
This is the most up-to-date and comprehensive assault on theism which I have come across. If you are prepared to take the trouble to read it, it will leave you in no doubt that the theistic position is untenable.