According to scripture, they are. God is immutable and so is His moral law. The nature of man has not changed, nor has God's decrees about how man can achieve happiness in this life and the next. The moral law isn't imposed as a set of "rules" for unthinking beings. Through faith and grace, the formation of conscience and an understanding of their purpose, a Christian will understand the way to live and accept it with joy - no matter how difficult nor the self sacrifice involved.