Catholics can no longer believe that all Muslims, Hindus, atheists and so on are going to hell. We have this on the authority of the former Pope Benedict XVI, who gave a long interview a couple of years ago that has only just surfaced in English. Benedict’s view must be definitive, not just because he was a pope, but because he was a notably conservative one.

Remove the threat of hell for people who are honestly mistaken, and you have a problem: if you don’t have to be a Christian to be saved, what is the point? This is a question that really troubles Benedict. It has led, he says, to a “deep double crisis” in the church. First, it takes away the inspiration for the heroic missionary efforts of the past, and indeed takes away the point of being a missionary in the future. Worse than that, though, it raises the question of why anyone already a Christian should bother to keep it up when they are going to heaven anyway.

The pope emeritus is not the first person to raise this question. It is a commonplace of the sociology of religion that hardline sects, which really do believe that everyone outside them is damned, can demand much greater commitment than those that simply think it would be nice if everyone were right. One reason that the world is full of intolerant fanaticism is that it works. Believing wicked things gives you the energy to propagate them too.

But the old pope can’t go back. He can’t believe that untold millions are being tormented forever by a loving God just because the same loving and omnipotent God arranged for them to be born in countries that are not Christian. So what can he believe? The answer is quite incomprehensible to me, but before he gets there, he considers and rejects two perfectly straightforward and popular explanations. The first is the idea of the “anonymous Christian”, which comes from the German theologian Karl Rahner. This says essentially that anyone who sincerely opens themselves to God has grasped and is practising the essence of Christianity. Since God, in this view, is the essence of humanity, “The Christian … coincides with the human and, in this sense, every man who accepts himself is a Christian, even if he does not know it.”

But that’s not good enough for Benedict because it takes no account of the need for conversion, for “the drama of change and renewal that is central to Christianity”.

Still less will he tolerate what many people actually believe, which is that all religions walk a path towards the same God. He prefers the straightforward view of the Bible and the early church, that all other gods are idols or in fact demons, something that inspired a wonderful passage in Paradise Lost where the fallen angels leave hell to take the form of gods and to corrupt the world – “First Moloch, horrid King, besmeared with blood of human sacrifice and parents’ tears” – but if this is taken literally it’s very hard to see how these demon worshippers could be saved.

In the end, Benedict seems to take refuge in the idea that God keeps the world going because of Christians, and that we are all here because some people at least have grasped the true religion: “It is important to mankind that there is truth in it, this is believed and practised. That one suffers for it. That one loves. These realities penetrate with their light into the world as such and support it. I think that in this present situation it becomes for us ever more clear what the Lord said to Abraham, that is, that 10 righteous would have been sufficient to save a city, but that it destroys itself if such a small number is not reached.”

It’s easy to laugh at this, but in some form his dilemma is shared by all universalist theories about what people really need to be happy in a world that is profoundly multicultural. Traditionalists such as the pope believe that liberal self-actualisation is a delusion that can only lead to misery; feminists and egalitarians are sure that no one can be completely fulfilled in a patriarchal and hierarchical society. It’s not just popes who find it hard to believe that there are many ways to salvation. We are all guilty.