I really don't get why people are so bothered by it. Not only is it rated 18 (and it's an official rating in the UK, so under 18s shouldn't be buying it/be being sold it), but it gives you several times where it goes "are you SURE you want to play it?", so what people are doing is going "no, I won't be offended at all" and then getting offended, which just reeks of stupidity to me.
If you were stupid enough to select that you wanted to play it and wouldn't get offended, and then got offended, you aren't entitled to an opinion in my book.
However, note that the "Christian" is an ex-Bishop, and therefore not a representative in any way of the Anglican Church. The Anglican Church as a whole generally ignores this sort of thing and sticks to what it's meant to do, which is cater to it's own membership. Hell, given that the Archbishop of Canterbury out-and-out stated that evolution did happen and that the Bible was wrong/a metaphor to explain a complex series of events that took place over millennia to people who wouldn't understand, I doubt he'd actually come out and speak, for the whole Anglican fellowship in the UK (which I am, all be it in name only, a member of), against a computer game that has violence.