Grounding for an Ethic?

Hi all. I have a (probably rather overrated) question. I am coming out of a christian world view, and am wondering what would others response be to the question of how does one, or from where does one, ground a theory of ethics? Is it in the self? Society? How do you say “this is why I am ethical” and “these are my ethics”. Thanks for all your help,

Jason

en.wikipedia.org/wiki/Normative_ethics

en.wikipedia.org/wiki/Descriptive_ethics

To make sense of them:

en.wikipedia.org/wiki/Meta-ethics

Start there, and start reading