Religious Pluralism is either descriptive or prescriptive. The descriptive version is merely the observation that there are many different religions. It is hard to imagine anyone disagreeing with this premise. However, prescriptive pluralism is what appears to be implied by such an observation.
Since there is so much disagreement between religions an explanation must be provided for such diversity of opinion. Either one group are correct and everyone else is mistaken or something else is going on. Given the apparent parity between the religions (all religions are made up of human beings who claim to have some truth about god or gods and ground such beliefs in religious experience, various kinds of revelations etc) and that there is no way to arbitrate between religions since there seems no neutral vantage point from which to evaluate the claims. This is what we have so far:
(1) There are many different religions (descriptive pluralism)
(2) As far as anyone can tell there is rough epistemic parity between the people in these different religions
(3) Therefore, all or most religions have some justification for what they believe
The prescriptive version of religious pluralism is an attempt to explain (1-3). The best explanation, pluralists claim, is that no one has superior access to the truth of the matter; they only have access to their perception. This leads to the claims:
(4) No one can know God as he is in himself
(5) People only know their perception of God in their own religious context
(1-5) entail, for prescriptive pluralists, an obligation for all religions to reduce their confidence in the exclusivity of their claims. This, I think, is at the heart of John Hick's prescription:
That there is not just one but a plurality of such historical channels is prominent among the facts for which an interpretation of religion must account. In doing so it will inevitably have to go beyond the dominant self-understanding of each tradition. For each has come over the centuries to regard itself as uniquely superior to others, seeing them either as lying outside the sphere of salvation, or as earlier stages in an evolution of which it is the culmination, or as less full and authentic versions of itself. But this cannot be sustained on impartial grounds. A genuinely pluralistic hypothesis will thus inevitably call, at least by implication, for further development within each of the traditions... insofar as each of the world religions comes, in today's global city, to see itself as one among many it will use these methods to de-emphasize its own absolute and exclusive claim, allowing this to fall into the background and eventually to become absorbed into its past history.Prescriptive Pluralism allows no room for exclusivity in religious belief. Its claim is universal and applies to all religions. Moreover, its claim is absolute and requires those who disagree to change their view in the face of the obligation to be rational. As prescriptive pluralism advances its own totalising instinct becomes all the more obvious. At root, Religious Pluralism is no mere suggestion for a description of reality, but a prescription for society:
(6) All religious believers should lower their commitments to exclusive claims
The trouble for prescriptive pluralists is that not many religions appear to be willing to reduce their confidence in their exclusive claims. For example, many Christians still argue that Jesus is the only way to the Father. What one really needs is a political system that would insist that all are equally valid and that no one religious group can know the Real in itself and have a sole grip on the truth. Some, for example, have piggy backed on American ideals to ensure lawmakers legislate against exclusivity (apparently blind to the consequence that such laws create a new, and far harsher, exclusivity).
Alistair McGrath calls the prescriptive proposal, “tantamount to intellectual Stalinism” since it is rooted in the modernist totalitarian urge to organize the raw material of culture, language and ritual according to human desires: “In making this assertion, I am deliberately pointing up the common modernist agenda and roots that underlie prescriptive pluralism, Nazism, and Stalinism.”
Oddly enough, such charges--of totalitarianism and intellectual oppression--are often made by prescriptive pluralists to religious exclusivists. On the face of it saying "everyone is correct" sounds more tolerant than saying "one is correct and all the rest are wrong." Of course, it does not take long to see that prescriptive pluralists are just as exclusive in their beliefs as everyone else. The difference is that they, like many other ideological purists before them, wish to impose their beliefs on everyone else. And this is often done by force.
For Christian exclusivists, there is no trouble, in principle, to acknowledge the diversity of religion and remain committed to the exclusivity of their own commitments. One can be a descriptive pluralist and not be a prescriptive pluralist. I can believe that there are many different religions, but that one religion is correct. This does not necessarily entail intolerance toward those who believe differently to me if the religion I do believe in extends a worldview that accounts for non-belief and exhorts good treatment of those who believe differently than myself. I think that Christianity, in principle if not always in practice, contains such resources.
Furthermore, Christians can both "tolerate" other religions and argue with them in strong terms without that leading to a forced imposition of religious commitments. For example, Christians can condemn prescriptive pluralism as not merely a possible way in which to make sense of the existence of multiple religions, but, rather, the Satanic root of all rebellion against God. It is Satan's greatest ploy to put God to the test. Satan persuaded Eve to make God's interpretation of reality a hypothesis, he even attempted to make Jesus do the same in the wilderness (Mark 1:12; Matthew 4:1-8; Luke 4:1-13). Such hypothesising by sinful human beings is what leads us to set up idols, other gods. And it is hypothesising by prescriptive pluralists that is so deeply sinful. They seek to explain the world in terms that a priori rules out the truth of God's word.
However, none of those harsh words mean that Christians should force others to be Christians through coercive policies, forced conversion and alike. It might mean, however, that Christians will vote for people who best represent their moral views and this might lead to restrictions to abortion rights, marital definitions etc. This is no way forces anyone to be a Christian; it only restrains evil. And that, by the way, is what God establishes governments for (Rom 13). To deny Christians access to democratic processes because they hold to exclusive claims would be irrational, but, in our era of irrational policy making, not out of the question.
The fear of theocracy that many throw around in critique of Christians is misguided. Many feel that Christians wish for the church to arbitrate laws and societal structures. Although this has been the case in the history of the church it is not an essential belief for a Christian. In fact, I would argue, it is a misguided belief for a Christian. The church does not stand over the state, only God is over the state. God, not the church, establishes nations and governments (Rom 13; Acts 17). The church is not a state; it is a people called out by God from all nations, gathered as the worshipers of the one true God.
However, Christians do recognise an arbiter of truth, one who will judge the claims of every religion. For Christians, there is an arbiter of truth - God himself. And we are responsible for what God has revealed to us. According to Paul such a judge as is required to arbitrate between truth claims has already been established. In Paul's address to the Areopagus, Paul asserts that Christ has been established as the judge of all religion, all worldviews (Acts 17:31). Truth will not be self-attesting, but attested by Christ in whom is “hidden all the treasures of wisdom and knowledge” (Col 2:3).
The prescriptive pluralist essentially sets himself up as god, the arbiter of right religion. To say that no one knows is just as authoritarian as saying some know and some do not. The difference is that the prescriptive pluralist sets himself up as the originator of truth.
For more on the pluralistic hypothesis see my writings on John Hick.