From Covenantal Apologetics by K. Scott Oliphant, the seventh tenet in a list of “ten crucial theological tenets for a covenantal, Christian apologetic”:
7. There is an absolute, covenantal antithesis between Christian theism and any other, opposing position. Thus, Christianity is true and anything opposing it is false.
This should be obvious to any Christian, but it is oftentimes not as prominent in our thinking as it ought to be. When we claim to be Christians, we are doing more than just listing a biographical detail. We are claiming that the truth set forth in God’s revelation describes the way things really and truly are in the world. That is, we are saying that what God says about the world is the way the world really is.
Any view or position that opposes what God has said is therefore, by definition, false and does not “fit” with the way the real world is. This means that the views of any who remain in unbelief are, in reality, illusions. They do not and cannot make sense of the world as it really is. Not only so, but, we should notice, there are at bottom only two options available to us. Either we bow the knee to Christ and affirm the truth of what God says, or we oppose him and thus attempt to “create” a world of our own making. No matter what kind of opposition there is to Christianity, before we even know the details of that opposition, we know that it cannot make sense of the real world. We know that it is self-destructive.
This is a great comfort and should help us to be more confident of our defense. We need not fear or be threatened by any view that we encounter. Even before we know the details of that view, we know from the outset that it cannot stand of its own weight; it cannot match the way the world is. When we begin to learn the details of an opposing view, then, we do so with the initial conviction that there will be no way for that view to actually make sense of the real world. Any view that opposes Christianity cannot be consistently thought or consistently lived.
I’ve already posted the first tenet in this list of ten.