The relationship between religion and morality

The Bible contains many passages that seem immoral to follow. For example, Exodus 21:20-21, Leviticus 25:44-46, Ephesians 6-5 and Titus 2:9-10 all endorse slavery. I Corinthians 14:34 commands women to stay silent in church. Deuteronomy 22:28 states that when a virgin has premarital sex (the text is vague about her consent, so the sex could be consensual or non-concensual), she must marry that person (and can never divorce). Why do we no longer follow these commands? And more important, what does this tell us about the relationship between religion and morality? Explain.