As Christians, the Bible is our infallible guide for spiritual growth (2 Timothy 3:16-17). This includes the Old and New Testaments. We may not be under the law like the Israelites nation was, but we can still turn to the Old Testament as a guide for morals and ethics. For us today, the teachings in the Old are just as valid as the teachings in the New. Because Christ affirmed the morality of the Old Testament (see Matthew 5-7), I believe that we should too.