The right thing and the wrong thing. Determining which is which often depends on which guru you follow, which experts you believe, what your church or country club endorses...
Some wrong things seem obvious. Beating your child, for instance, although the Old Testament clearly condones it. Helping yourself to something that isn't yours, although quasi-historical characters like Robin Hood put a different slant on that. Is it okay to rob a thief? Is it absolutely altogether clear who owns what? If I stole some ancient pottery shards from a museum and gave them to the tribe whose ancestors made them, would that be the wrong thing to do?
Here in America murder is illegal but the majority of our states have capital punishment. And we send young people overseas for the express purpose of killing other people. So, whether or not killing people is right or wrong depends entirely on which people you kill and under what circumstances you kill them.
Cigarettes have been killing people for years yet I've never heard of any tobacco company CEO being imprisoned. Or executed.
Some people thing that having an abortion is a form of murder. I'm not saying it is or isn't. All I'm saying is that killing, in our culture, is not an absolute wrong.
Falling in love and/or having sex with someone of your own gender is wrong if you take the Old Testament literally. This is the same Old Testament that says it's okay to beat your child senseless (Proverbs 13:24, 23:14, 22:15), to engage in incest under certain circumstances (Genesis 19:30), or offer your daughters to be raped (Genesis 19:8).
What if there really is no such thing as a priori right and wrong? What if right and wrong are human-generated concepts?
Determining right from wrong really isn't that easy. Maybe the gurus and experts have made illogical and unsubstantiated claims. Maybe they have a hidden agenda. Perhaps your church's doctrine is outdated and your country club buddies motivated by personal gain.
Maybe the choice is ultimately up to you. Perhaps it requires you to think carefully, entertain possibilities that are in conflict with your most cherished beliefs. Maybe it requires that you imagine yourself (insofar as possible) in someone else's shoes. Perhaps it requires that, instead of moving with the crowd (your crowd), you act entirely on your own.
What can you do in the face of moral ambiguity? After listening, checking facts, consulting your imagination, utilizing both critical thinking and compassion, you make a decision that (possibly) will help some people and harm others. You aren't one hundred percent certain that your choice is the best one. But, in the absence of absolute certainty, it's the best you can do.