When a covenantal apologetic meets atheism or various other forms of obvious unbelief that divide between the two positions (in Adam and in Christ) is as bright as the sun. It is obvious and it lights the way for clear avenues to travel as we try to show the futility of those positions. But when the position that we are dealing with is a specific religion, matters can become more complicated.
There is no recipe for covenantally defending the faith among and with other religions. All religions have their own specific dogmas, codes, rituals, and worship. However, it does seem that, at least initially, three basic categories can help us focus our analysis of those religions and our conversation with those who hold them.
First, with Paul, we must be acutely aware of exactly who the god of the other religion is. Because other religions exist in order to avoid the true God, they will inevitably interject another god, and that god will have distinct characteristics. This is more difficult to recognize, for example, in Buddhism than in Islam, but it is useful if we can focus, first, on the doctrine of god on which the false religion depends.
Second, it will help us to see how the false religion deals with its god's relationship to creation. Whatever that relationship, every false religion will inevitably posit either something like a god who is too far off to really relate to creation, as in Islam, or something like a god who is so close that we become gods ourselves, as in Mormonism. In any case, it is useful if we can pinpoint how the proposed god is thought to relate specifically to his creation and to us. What are the attributes or characteristics that allow (or do not allow) this god to relate to us?
Third, if we can understand something of the false religion's theory of revelation, that understanding may serve us well. This might require that we read the actual books, if there are such books, to which the false religion is committed. But such things can also be brought out in conversation with its followers.
It might also mean attempting to find out just how those books are what the religion claims they are. In almost every case, the books in false religions came to exist in some isolated, unobservable, and unverifiable way—for example, through Muhammad, by himself, over a period of twenty years or so; or through Joseph Smith, by himself in a barn. In understanding this, we have the opportunity to highlight the public and historical roots of Christianity in redemptive history. It helps, at times, to be able to point out that Christianity did not have its beginning in a private room or with only one prophet, or even simply at the time of Christ. Rather, it began "in the beginning," and it reached its climax in history in the coming of the Son of God himself in the flesh.
These three things often prove useful in discussion with other religions. They are not the only things to be aware of—certainly not all that we may need to understand—but they could be a good starting place.
ENGAGING WITH THE LAWRENCES OF YOUR LIFE
When I was a first-semester seminary student, a Jehovah's Witness came to my door one Saturday morning by himself (which was unusual, because they usually travel by twos). His name was Lawrence, and as he began to talk to me about his religion, I told him that I was a Christian and therefore believe that Jesus Christ is fully God, as Scripture teaches. Lawrence then told me that the verse in John 1:1 actually, in the Greek, said that the Word was "a god."
As a young and brash seminary student, I told him to hold on a minute. I went to my study and got my Greek New Testament. I then pointed him to John 1:1 and asked him to tell me exactly how he thought the Greek should read "a god" instead of "God." Lawrence lowered his head, looking ashamed, and said he did not know how to read Greek (of course, as a first-semester seminary student, I didn't know much Greek either). As I watched Lawrence, it was clear to me that he saw himself at that point as a failure. I felt compassion for him, especially because, truth be told, about all I could read in the Greek New Testament at that point was John 1:1!
So, in the midst of the awkward silence, I decided to change the subject. I asked Lawrence if he thought God is holy, perfect, and without blemish. Surprisingly, he said yes. Then I asked him how he thought this holy and perfect God was going to accept the likes of us when we are so unholy and sinful. Lawrence looked at me and said, "No one has ever asked me that question before."
Maybe Lawrence was new at this. Maybe his heart was not into what he was told to do at Kingdom Hall. Whatever the case, Lawrence and I had a great discussion about the gospel of Jesus Christ and how only in Christ can we be acceptable, and accepted, by a holy God. I watched as Lawrence walked away. He did not stop at any other door; he just walked and walked.
I don't know what finally happened to Lawrence. The point of recounting this is to remind us that what anyone needs, and this includes those who have been deceived into other religions, is the gospel of Jesus Christ. Had I been able to argue the fine points of Greek with Lawrence, I may have succeeded in showing him that I knew Greek better than he did—maybe even in showing him that his own translation of John 1:1 was questionable. But if I had discussed only that, I would have done him a disservice.
It is only the gospel of Christ that can change hearts. It may be that other religions are a fertile seedbed in which that gospel can be effectively planted (as God, in his sovereign wisdom, gives the increase). If so, then evangelism can often be the proper response to false religions. The gospel is the "power of God for salvation to everyone who believes" (Rom. 1:16). But that power must be communicated in order to be activated. We should never lose sight of that fact in our discussions.
But there are times when what is needed is a little "premeditation" in the context of our communication of the gospel. In those cases it might be useful to employ a covenantal apologetic, to defend Christianity in the context of problems and issues that false religions bring to the fore.
This piece is adapted from K. Scott Oliphint, Covental Apologetics: Principles & Practice in Defense of Our Faith (Wheaton, IL: Crossway, 2013), 225–233. Used with permission of the publisher.