I think this argument works well in a simple, straight-forward form. It's possible to see the sense of the argument, as long as you correctly understand the two premises. But, this argument can also get as technical as you'd like. Let's separate the straight-forward, common-sense of it from a little bit of technical material.
Common sense stuff
Put simply, we all have a conscience--a voice inside us that recognizes right and wrong. We know that that voice comes from something more than our own preferences or taste, because it often contradicts our preferences. I want to lie to protect myself, but I know that is wrong. I want to cheat on a test, but I know that is wrong. That "voice" inside convicts me. It bothers me. Sometimes, it won't let me sleep.
We treat this voice like the voice of God. It is certain and inarguable. Why? Because on some level, we intuitively know that it is the voice of God.
We can put this simple intuition more formally by phrasing it logically. A common formulation goes like this:
- If God does not exist, objective moral values do not exist.
- Objective moral values do exist.
- Therefore, God exists.
Let's look at all three parts. The first premise is that God is the only possible source of objective moral values. What do we mean by "objective moral values"? These are values of "good" or "bad" that do not change based on person, place, or time. For (a simple, extreme) example, it is always wrong to torture an innocent child. It does not become okay because the culture changes. It does not become okay because the people that did it lived a thousand years ago. It is just wrong. Period.
How can we say that something is always and everywhere wrong? There must be a point of reference. It can't come from a mortal person, because then it isn't objective. It can change when the next person comes into power or when that person's tastes change. It can't come from some universal concept of goodness. A concept has no power to compel us, and conscience is compelling. It can't come from our instincts, because we don't obey our instincts absolutely. We ignore them when we think better (or worse), such as ignoring the instinct to flee in order to help someone in danger.
There is only one viable source for these moral values, and we call that source God.
Objective moral values do exist.
The data for this argument is internal. We feel the pull of moral values, and we feel them regardless of our preferences.
Therefore, God exists.
This follows logically. If it exists, and it can only exist because of God, then there must be a God.
In the next post, we'll look at several more technical angles on this, for those of you who are interested. After that, we'll wrap up arguments for God's existence and move on from there. We've only proven, as Dr. Kreeft likes to put it, a very thin slice of God. We'll need to expand from a God that exists to a God that has some Godly attributes.
Dr. Peter Kreeft argues an intuitive version of the in The Argument from Conscience.
Michael Horner does a great job in this video, addressing some Misunderstandings and Objections to the Moral Argument for God.
For a more technical treatment, Dr. William Lane Craig treats the argument with formal logic in several Q&A replies, including Q&A 228: Formulating the Moral Argument and Q&A 349: The Moral Argument for God.
Update: Dr. Craig has a page dedicated to all his videos and articles about The Moral Argument.