I've always regarded 'ethics' as a 'Christian' field and have always associated it with 'morality'. However, I came across a few instances in which ethics have driven people to justify acts which were obviously contrary to the will of God i.e. morally wrong. This led me to seek a few answers which I have summarized below...
Ethics is defined as 'that branch of philosophy dealing with values relating to human conduct, with respect to the rightness and wrongness of certain actions and to the goodness and badness of the motives and ends of such actions'.
Morality is defined as 'conformity to the rules of right conduct.'
Don't you see the difference? Morality refers to an unchanging set of rules as to what IS right and what IS wrong, regardless of the society, culture, situation or era. However ethics is based on perception. Ethics weigh the pros and the cons of an issue or action from a human point of view - this balance may sometimes lead to a 'morally wrong' decision.
As Christians, we're not to focus on the 'ethics' of an issue, but its 'morality'. We ought not to weigh up its advantages and disadvantages i.e approach it with 'worldly wisdom' but focus on the truth explicitly stated in the word of God. The truth is unchanging, inerrant and infallible as it is from God - God makes the rules - however, we determine ethics, and if you haven't already noticed, we make mistakes!