Judge not that ye be not judged.
Do not judge, or you too will be judged.
Don't pick on people, jump on their failures, criticize their faults— unless, of course, you want the same treatment.
~ The Message
Matt. 7:1...one of the most overused, misunderstood verses in the Bible IMO. "Judge Not/Don't judge" is not where the period stops, after that simple yet overblown statement the justification of expecting that same judgement if you do judge follows! And what about the next couple of verses? I like how poetically the New King James puts it:
For with what judgment you judge, you will be judged; and with the measure you use, it will be measured back to you. And why do you look at the speck in your brother’s eye, but do not consider the plank in your own eye? Or how can you say to your brother, ‘Let me remove the speck from your eye’; and look, a plank is in your own eye? Hypocrite! First remove the plank from your own eye, and then you will see clearly to remove the speck from your brother’s eye.
Does this mean that our friends and family are allowed to continue in some sort of behaviour or actions that don't line up to God's Biblical instructions? Not in the least bit, 1 Thessalonians 5:14 tells us to admonish and encourage our brothers and sisters in Christ that are unruly, fainthearted and weak all with extreme patience on our end.
It's not easy telling someone you love they're out of line or wrong (and we're called to love all our brothers and sisters in Christ), but it's always worse to hear that you, yourself are the one out of line or living in sin. So yes, admonishment ("to caution, advise, or counsel against something especially in a mild and good-willed manner") among believers is something we're called to do but I can't stress enough how important the attitude of love is when it comes to correcting a friend. The heart really does have to be in the right place when approaching a friend with a reprimand.
So does this mean non-Christians are just getting a free pass to do whatever and we can't do anything to stop them? No, but it's definitely not our place to call them out on something that they don't adhere to. Think about it this way, you go out to eat with a friend that's a vegetarian and order a steak. They then sit there and scold you on the evils of red meat, how awful it is for you and how bad a person you are for eating a defenseless cow. You'd come away from that dinner thinking they were a self-righteous, pretentious, pushy JERK! It's the same when we correct a non-Christian that way, we come across as jerks!
Through example, communication and love people will see that we are different if we claim Christ and live it out (John 13:35). Never does it say they will accept the love and grace we owe our lives to by our reprimands and chastisement on their wrongdoings.