Understanding Necessary and Sufficient Conditions

One of the bigger misunderstandings when conversing with others is the issue of necessary and sufficient conditions. Recently, my friend Max Andrews posted an article to his blog entitled "The Incoherence of Claiming to be an 'Ex-Christian'". You can read the whole post, but basically Max argues that folks like atheists who hold that they were one Christians but now are not are actually stating a contradiction. To be a Christian, one must believe things like God exists and that the death, burial, and resurrection of Jesus Christ were real events. In fact, one must trust in those beliefs, relying upon them for one's salvation. You cannot be a Christian without being saved, so, salvation is necessary to be a Christian. And it is necessary to believe in God's existence and the resurrection of Christ in order to be saved.

The problem comes in, then, when an atheist says that he or she is not now a Christian. Atheists reject the very points that are necessary to be a Christian at all. But that's the rub. If you claim that you used to be a Christian, you are then saying that the concept of being a Christian can obtain. Thus, you are also saying that God does exist, that Jesus did die and rise again, and any other point that is also necessary for salvation also obtains. But at the same time, as an "ex-Christian" you are denying these very points!

As the comments on Max's article seems to show, there are a lot of people who are confused about the concept of necessary and sufficient conditions.  These distinctions are crucial in clear-thinking and I found a wonderful video that pretty clearly spells them out. I hope this will help you better in your conversations.