But where does that moral compass come from? If it comes from man then it's simply matter of subjective opinion. If it's written on our hearts and is an objective truth, then it must come from a creator.You don't have to be a Christian to have a moral compass, but it doesn't hurt.
There definitely are some people who live right that are not active in a Christian Church. Years ago, I dated a very clean living, kind, loving woman that was an Atheist. Not against God, just did not believe. Very rare.
She is simply stealing her morality from God. Living by a moral standard and ignoring where the standard comes from doesn't nullify that it exists.