Can God Be Known By Natural Reason?

Hello everyone and welcome back to Deeper Waters. I’m still in the process of updating the site. The work of the HTML on the blog itself is quite difficult. Hopefully that will be up and running before too long. I’m also always open to suggestions on what can be done to improve Deeper Waters. We’re going through the doctrine of God now and we’re using the Summa Theologica. Those who do not have a copy can read it at We’re studying how God is known by us and we’re on the twelfth article now.

Can God be known by natural reason? In other words, when you’re out in the world and you meet the non-Christian who does not accept the revelation of God in Scripture in anyway, can you use natural reason to show the existence of God at least? Is it possible by philosophical ideas and the study of the world around you to come to the conclusion that God exists.

Something to note is that when these kinds of arguments are given, it’s not necessarily to prove the Christian God. These arguments are necessary for Christianity to be true but not sufficient. After all, God must exist for Christianity to be true, but it could be true that God exists and he’s Allah in Islam. (I do not think for a moment such is true, but the point is there for the sake of argument.)

Aquinas argues that we can know God by natural reason. Now this doesn’t mean we can know all about God. Some things about God cannot be known by natural reason, such as that God is triune or that God has revealed himself in Jesus Christ, but some things can and many such things were found by the pagan philosophers before Christ, such as Aristotle.

For Aquinas, there are no a priori ideas. We are not born with knowledge. All our knowledge arises from sense experience. Now sense experience will not get us to see the essence of God, but sense experience will get us to the point where we can better understand the essence of God.

The way of understanding God in Thomistic thought is really not understanding what he is, but understanding what he is not. What is it about God that makes him distinct from his creation to the point that he doesn’t even need to be created? For instance, when we look at divine simplicity, we come to the conclusion that God is not composed.

This was also the evangelistic method that Aquinas held to in his own life. When one was debating the heretic, one could use the New Testament and the Old Testament for even heretics often accepted them as valid. When debating a Jew, one used the Old Testament. When debating a Muslim, reason would be used. Today, there are many other groups we’d add to the list besides Muslims.

Aquinas is also noted as saying that his arguments are not just based in documents of faith but on the reasons and arguments of the philosophers themselves. This is a lesson we need to learn. It does no good to argue with an opponent from what you accept as an authoritative source and he doesn’t. Quoting Scripture will not work on an atheist who doesn’t accept Scripture. Using the arguments of the philosophers themselves is different and it should hopefully if they submit get them to the point that they will submit to Scripture, the ultimate authority.

This isn’t to limit Scripture of course, but to help us see how we should debate with an atheist. If you don’t think so, just consider how effective it is to you when you have the Book of Mormon quoted to you or when you have the Koran quoted to you.

We shall continue tomorrow.

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