I find it interesting how Lewis can use logic to prove a biblical truth. Sometimes I wonder how one could defend the faith without the use of the bible but when I read Lewis I realize how logic can be used to support a biblical principle. In the first chapter of Mere Christianity Lewis supports two simple statements and expounds upon them. He explains that there is the existence of a Moral Law, a natural law defining what is right and what is wrong. He also shows that we all try to hold others up to this Moral standard but cannot keep it ourselves. This is the basis for the argument that man is fallen and needs a savior for redemption.
It is easy for a Christian to explain the need for a savior. All he needs to do is to visit certain passages as Romans 3:23 or Romans 3:10. All we need to do is see that we cannot keep the law set before us by God. We cannot possibly keep every law in the Old Testament and therefore have not lived up to God’s standard. God had mercy on us and sent his son to die for us so that we could have a relationship with our creator. For one who reads and believes the book of John, all this comes very easy. It is stated simply in the bible. Although it may be hard come to terms with the content involved in the gospel message, it is still stated clearly. What is more difficult is to prove, without the bible, that there is indeed a law that has been broken making us imperfect and sinners.
Lewis explains that the Moral Law is similar to the laws of the universe. Just as the law of gravity determines that a ball will drop, the Moral Law determines right and wrong. The presence of this Moral Law is embedded into each and every one of us. We feel guilt when we do something wrong and thus know we have broken the Natural Law governing our morals. Now, some may say that these feelings of guilt are byproducts of social training. That our parents and teachers taught us that things such as stealing, murder, rape, were bad things. Thus we should feel guilt after committing such acts. Some may also continue by saying that other people have different definitions of what is good. For example, Hitler and the Nazi’s were trying to improve the world by ridding it of Jewish blood. This argument can be refuted through the idea of progress.
The Natural Moral Law is much like the law of mathematics, they improve with time and truth will eventually be determined. Throughout the ages mathematicians have come up with different theorems and laws, some were wrong and some were right. As time went on the incorrect ideas were discarded in favor of the ones that were determined to be true. In the same way, many different cultures have had different definitions of what is morally wrong but the simple fact is that every culture has believe theft, murder, rape and other such things to be wrong. Thus, moral ideas progress, the good ones are kept while the bad ones, such as genocide, are discarded. Although there are occasional times where society believe certain evils to be tolerable, the same Moral Laws prevail.
Based on the Law of progress we have certain timeless moral laws which we must follow, as fallen creatures, however, we cannot help but break them. Although we expect others to live up to the same laws, we realize that we ourselves break them. We break them through the simplest things as a selfish act, a petty lie, or sometimes the bigger things such as rape and murder. As the violators of a Moral law we are helplessly imperfect. And that is why we have a need for Jesus Christ.