Non-Christians just don't "get it."

In 1 Corinthians 2:14 the Apostle Paul says " But the unbeliever^[a] does not welcome what comes from God’s Spirit, because it is foolishness to him; he is not able to understand it since it is evaluated^[b] spiritually. " What this means is, it does no good to argue spiritual things with a non-Christian because he just doesn't "get it." I've told my Sunday School Class many times it's useless to use the Bible as an argument when your opponent doesn't believe the Bible. This is why we usually lose the arguments on homosexuality, abortion, etc. when we argue with non-believers. If they don't accept our authority, then the are not swayed by it. The best we can do is to try to win our opponent to Christ, first. A good study of Biblical apologetics works here, too. We must show the authenticity of the Bible before the skeptic will accept its arguments. Prayer is the best method to use. Pray that the Holy Spirit will convict the person to at least listen.