Unless you believe in a soul. Actions don't always give intent. I can do the right thing, at the right time, for all the wrong reasons. And as for actions, I believe there always exists a scale of gravity and a scale of culpability. Apart from anything a person does or does not do, I believe they have infinite value, because Infinity gave His Life for their souls. I believe at any point in time, there exist the potential for a person to become the person God created them to be, and the person that currently is. I believe the "person that currently is" is on a journey either moving closer to the "person God intended them to be", or further from that picture, based solely on free will choices made, how much that person has cooperated with grace, how much that person has surrendered to Divine Will and allowed self to be transformed. I believe as long as a person is alive, there remains a possibility that Love can break through and that person can allow change towards becoming what God intended. Simply, God's Mercy is greater than our weakness.
People are more than thoughts and actions. I can judge an action without judging a person. I can judge your work performance without judging you, because perhaps with more training and better instruction and communication, trapped inside you is an awesome employee just needing formation. No different, and that is an example you should clearly be able to grasp.
Sin is pretty much black and white - an action, thought, or deed either is a sin/sinful, or it is not. Not sure how labeling an action as sinful or righteous, legal or illegal, right or wrong automatically equates to casting judgment on a person. We might all agree that theft is illegal, but if a father who's been out of work for 3 months while searching and begging for work daily, and his family hasn't had a meal in 3 days, if he steals enough food from a garden to feed his family, I don't see how calling his actions illegal (or sinful) casts judgment on who he is as a person.
I didn't write the law, yet even if I believe that man to be the greatest man alive, I can't simply chose to believe his action did not break the law. Yet my judgment of the man does change by stating he broke the law. If you are late to work, and I say "you were late to work", I'm not casting judgment on you; I'm simply pointing out you were indeed late for work. Whether you partied all night and didn't go to sleep at a responsible time or if you had a blowout and you're covered in grease with the flat tire in the back of your truck doesn't change the time you got to work. I just think you have issue with the word "sin", a word I don't believe I've used.