Romans 2:12, 14-15

For as many as have sinned without the law shall also perish without the law: and as many as have sinned under the law shall be judged by the law

(for when Gentiles that have not the law do by nature the things of the law, these, not having the law, are the law unto themselves; in that they show the work of the law written in their hearts, their conscience bearing witness therewith, and their thoughts one with another accusing or else excusing them)