How should we view religions other than our own? Do they contain truth at all? Or some truth? Is that truth just offered as part of a bigger lie that the remainder of the religion offers? Or can we learn from other religions while maintaining some sense of our own better views?
These questions matter, and thankfully, in Introducing Theologies of Religion, Paul F. Knitter presents a compelling, Christian theological model for doing so.
To answer these questions well, we need to first decide on our own philosophy of religion. Thankfully, philosopher Paul Knitter has provided a useful model for the ways that one religion may view the others, or how they share or do not share truths. We should each try to find our position in Knitter’s spectrum of five views so that we may have a position from which we can evaluate the religions. 
Knitter proposes five different views that range from very narrow and exclusive to very broad and inclusive, and most of us will find ourselves somewhere in the middle. The two main attributes that define these views are how they view the common (empirical) and revealed content of other religions, as we discussed above. Do other religions have any common wisdom we can value? And is their revealed content to be taken as true, or necessary for salvation?
As you read the descriptions below, decide where you currently stand. A summary of the views concerning these attributes is shown in Figure 3 below, listed from most strict to the most accommodating. The three important terms that help define the views are their positions on three key doctrines:
- Common Truth: Do other religions have any common wisdom worth acknowledging?
- Revealed Truth: Do other religions have any revealed truth about God?
- Salvation: Do other religions offer any genuine truth that can save their adherents from the consequences of guilt, especially guilt before God?
Let’s look at these viewpoints in more detail.
1. Total Replacement (TR)
In this austere view, there is no common truth, revealed truth, nor salvation in other religions – they must be replaced, truth replacing lies. Not only is there nothing to learn from others, but their contents are largely created as half-truths, lies, and deceptions to lead men away from the truth. Often considered to have demonic origins, they are like a stained blanket that cannot be cleaned but must be discarded, no matter how much comfort and warmth they have provided. This view is often held by those labeled “fundamentalists,” though not exclusively.
2. Partial Replacement (PR)
While seen as a possible subset of the first view, this view deserves its own place in that it is probably where most religionists will land and still feel safe about the verity and exclusivism of their faith. In the PR view, there is general revelation in other faiths but no salvation or even partial salvific possibility. We can learn common wisdom from them, but nothing about the life to come or other revealed truths.
The benefit of this perspective is that it not only puts us on a peer-to-peer level of information exchange rather than a patronizing one-way proposition (“we are here to teach you”), it allows us to extend our knowledge of at least common wisdom.
Regarding salvation, however, the best other religions might provide for their adherents is an awareness of the right questions, but the incorrect answers.
This view allows for an increased presence of truth in other cultures and religions, but largely as a preparation for the complete answer – that is, for a later fulfillment. In Christian theology, this is called a preparatio evangelica – preparation for the good news. This is how Christianity views Judaism, and how Islam views both Judaism and Christianity.
This gray zone allows that God may be revealing specifics about his nature and plan of salvation, and there is a possibility that those who are dedicated to the “light that they have” may avoid any final judgment.
One intellectual, logical benefit to this viewpoint is that where religions disagree on revealed truths, we do not have to hold the illogical position that mutually exclusive claims can all be true. You may claim that where they disagree, some or all are incorrect. The question of whether or not the later religion is actually a fulfillment or more complete revelation, however, must be investigated.
This view may be characterized as “many true religions that need one another.” Not only does it admit that both general and salvific revelation are present in other religions, but it also assumes that no one has the full picture, and we need to learn from one another like blind men examining an elephant.
The upside of this view is that it is inclusive and aligns with the admirable humility to admit that we may be wrong, or only partially right. It does, however, make the search for a trustworthy source of spiritual truth somewhat impossible, and leaves us alone to have to figure it all out, counting all paths as equally likely, which seems logically contradictory. Some religions seem vastly different or wrong, though we may consider a handful to be possibly true.
This most inclusive view may be stated as “many true religions that do not need one another and can disagree.” This view is very postmodern and is predicated on the view that we cannot comprehend God, or the “Real” directly, but can only interpret the appealing to the higher emotions or to the aesthetic sense : SPIRITUAL More in a secondary fashion. Since our comprehension is largely subjective, differences in theology are explained as differences in subjective understanding, not in differing objective realities.
Again, the upside of this view, like the mutuality view, is that we can easily refrain from judging others as wrong, which feels good and humble. The downside of this view is that we may have to claim that no one can know the truth about God, and we must all have our own subjective opinions. And if religions make mutually exclusive claims, we must claim ignorance of how to evaluate them because, in this view, objective truth about God and the life to come either does not exist or is largely unknowable.