The claim under investigation is that Christian belief is unreasonable, unjustified, or unwarranted. We saw in Part 1 this objection is understood best as the claim that Christian belief lacks warrant; it is produced by brains that are malfunctioning (Marx), or functioning properly but aimed at something other than truth (Freud). In Part 2 we examined the concept of warrant more closely – what it is and how it works. Part 3 offers a way in which theistic belief could have warrant. Theistic beliefs are general beliefs about God (like the general belief that God exists, that the universe was designed by God, etc.).
As a reminder, this series is based in large part on Plantinga’s Knowledge and Christian Belief (144 pages). For a further treatment of these ideas, look there. For an even more in-depth treatment, see his magnum opus Warranted Christian Belief (528 pages).
In answering the question, we seek a model that, if true, grants warrant to generic theistic belief. The French reformer John Calvin held that, “There is within the human mind, and indeed by natural instinct, an awareness of divinity.” Calvin called this our “sensus divinitatis”. This capacity in humans doesn’t show up immediately; it occurs with maturity. We likewise don’t understand arithmetic in infancy; such knowledge comes with age. The idea is that this sense of God, our sensus divinitatis, produces belief in God under a variety of circumstances.
Colorful sunsets are part of what drew me to photography. There’s just something about them – they’ve got that quality that makes you want to stop everything and stare. In these moments I often find myself thankful to God, thankful for allowing me to be a part of such a world, for allowing me to witness such beauty. In addition to the glories of nature, there is also an awareness of being sinful and condemned before God (or even forgiven). So this divine sense, our sensus divinitatis, produces theistic belief in a variety of circumstances.
Here it is important to note two things. First, these beliefs are not arrived at by way of argument. One does not look at a beautiful sunset and then infer that such a person as God exists. That is not how the model works. Instead, theistic belief is directly produced in the context of such experiences. The belief naturally arises; it occasions itself in us. It isn’t an inference or the conclusion of an argument. Second, according to the model, our sensus divinitatis is damaged or weakened by sin. The effects of sin have caused our innate sense of God to malfunction. Sin would be analogous to a brain defect (like an inability to tell right from wrong). The model flips the Marx/Freud objection on its head; it’s really the unbeliever that has a cognitive defect with respect to religious belief.
Is Theistic Belief Warranted?
If theism is false – if God does not exist – then there is no such being or person as God. As a result, there is no such thing as a sensus divinitatis. If God does not exist, “it is unlikely that belief in God is produced by a process that is functioning properly . . . according to a design plan successfully aimed at the production of true belief .” So, if theism is false, theistic belief likely does not meet the conditions of warrant mentioned in part 2.
However, if theism is true – if God does exist – then there is a benevolent creator and designer of the universe. Given that this being loves and wants us to know Him, the chances are excellent He would create us with the ability to do so. It is natural to suppose that He would give us a sensus divinitatis or something similar. But then theistic belief would meet the conditions of warrant. So if theism is true, theistic belief likely is warranted.
An Interesting Conclusion
As a consequence of this, warrant with respect to theistic belief depends upon the truth or falsity of theism. The question of whether theistic belief has warrant is not independent of whether theistic belief is true. Hence, the atheist that claims theistic belief is irrational or unwarranted must be claiming that theism is false. To that we might be inclined to say, “May the odds be ever in your favor.”
The question of whether theistic belief has warrant is not independent of whether theistic belief is true.
In summary, we saw that, if God exists, we were designed with a divine sense that, when working properly, produces belief in God in various situations (like gazing upon the glories of nature). Then we saw that, if theism is true, something like this model is probably true. Lastly we saw that objections to theistic belief reduce to arguments against the truth of theism.
In Part 4 we will attempt to extend this model to include belief, not only in generic theism, but full-blown Christian theism.
 Plantinga, Alvin (2015-04-13). Knowledge and Christian Belief (p. 39). Wm. B. Eerdmans Publishing Co.. Kindle Edition.