I was asked a similar question a few days ago, and Jesus was asked a similar question 2000 years ago. And my answer was His:

Matthew 22:36-40(NIV) "Teacher, which is the greatest commandment in the Law?" Jesus replied: "'Love the Lord your God with all your heart and with all your soul and with all your mind.' This is the first and greatest commandment. And the second is like it: 'Love your neighbor as yourself.' All the Law and the Prophets hang on these two commandments."

In Jesus' own words (translated) we have the answer you are looking for. There is an absolute Ethic. God did write it, but more-so, God is it. "It" is Love. The written Law is, as it were, a lens through which we are supposed to see what it means to love God and our neighbor. If we understand it perfectly, we will understand love perfectly. If we then follow it perfectly, we will love perfectly. But Jesus went even further than that. Jesus made the audacious claim that if we first love perfectly, we will already be following all the Law! But, sadly, we are weak and broken people, capable of neither perfect understanding nor perfect love. What can we do?

We can attempt both; let both the Law of The Word and The Law of Love guide us in the light of prayer and discerning the will of the Spirit.

Feeling Inspired in Christ,
~CSL