A person can keep the moral law stated by St. Paul (Romans 13:8-10) by nature (Romans 2:11-16). I think great care must be taken when comparing overall principles of fallen humanity vs. the conduct of each individual (do not judge per Matthew 7:1). I think the answer is in John 3:16-21 in which the Lord indicates some will find him by faith & subsequent good works or others will at least find the truth by having a natural disposition to do good. Those who do evil, I would think, constitute the condemned unbelievers. Again, I believe we must take great care in discussing parameters laid out by the Lord vs. the conduct of our neighbor. We do not assume our own salvation or know who might be condemned.