I know some impressively honest atheists. My dear father was one (until he later came back to the Catholic Church.) Msny factors go into conscience including your temperament, your training early in life, the example of those around you, and your reflections on the consequences of your actions.
Proponents of Natural Law (this would include many Christians, Jews, Hindus, etc) are convinced that there is some drive toward moral evaluation built into the human "wiring," which can be sharpenend by reasonable reflection. (Says so in the Bible, too.) You're proof of that!
It's quite possible. Of course I believe they've found a predisposition to religion too. I wonder if they're related.