The Christian Moral Life - US Catholic Catechism
One common misunderstanding about Catholic morality is the idea that it comes from our religious beliefs (and thus has no place in the public square). The truth is that as Catholics we believe that the moral law is accessible to everyone through reason alone (but God's revelation sure helps in understanding it!). This is because morality is based on what human beings need for full flourishing, both as individuals and as societies, built into us and the world by the design and plan of God.