In the Bible, the guiding principle from Jesus seems to be that of love, ultimately shown in his sacrifice for us.
'This is my commandment, that you love one another as I have loved you' (John 15:12)
'Love is patient; love is kind ... [it] rejoices in the truth. It bears all things, believes all things, hopes all things, endures all things' (1 Corinthians 13:4-7)
Love is the motivating factor for us to decide how best to apply to moral situations and principles (Catholics too)