quote:
If man is merely the product of mutations in animals, rather than the special creation of God, morality is just an abstract concept, with no standard, or guidelines of behavior, from an authoritative source.
Or, you could look at it from another point of view and say that while morality is just an abstract concept, this only means that the standards we use must come from our social and practical reality. Thus we should strive for the most compassionate and altruistic morals because they bring desirable/good results.
Using an external source is no excuse to ignore the results of your actions. Flipside: Non-Christians can, and often do, follow the teachings of Jesus because they bring good things even if they do not agree with his divinity.