One of interesting things about God is the fact that God is love, and God is also the judge to whom we will all answer for our actions when we die. Some people have a hard time wrapping their minds around the idea that God can be both loving and judgmental. They think that love and judgment are mutually exclusive. They could not be more wrong.
Without judgment, there can be no justice. Without justice, there can be no meaningful love for the victims of injustice. Therefore, true love demands judgment --- specifically, judgment of those who would cause harm to others.
Once a person accepts the idea that love and judgment are not mutually exclusive, and that in fact there are situations in which it's impossible to be truly loving without being judgmental, then it's easy to understand how God can be both loving and judgmental.
It should also be easy to understand the idea that our own moral obligations include the obligation to deal with one another in a manner which reflects God's character. If indeed God's love for innocent victims is the motivation which causes him to judge people who would victimize others, then it logically follows that we likewise have an obligation to intervene in such situations --- and to judge and punish others for their harmful acts when such action is appropriate.
Who determines what counts as "harmful" acts? Do we finite human beings have the authority or wisdom to do so? No.
We may rationalize certain sins by saying that "no one really got hurt," but God is in a much better position to assess the damages caused by sins than we are. Many of the acts considered "harmless" by hedonists are in fact very harmful.
Sexual sin, for example, destroys families. Contrary to the teachings of morally depraved people such as Hugh Hefner, fornication and adultery are not harmless little indulgences which hurt no one. Sexual intercourse which doesn't occur within the context of marital commitment has wide-ranging societal consequences, not the least of which is the proliferation of single-parent families in which children are deprived of the ongoing support and guidance of both father and mother. Such deprivation is everybody's business, inasmuch as it statistically leads to increased poverty and crime. Therefore, telling people to mind their own business, when they criticize others for their sexual sin, amounts to a failure to really grasp the significance of such sin.
The same principle is applicable to many other so-called "private" sins as well.
Saying that we are sometimes entitled or even obligated to judge others is not the same as saying that we have unfettered freedom when it comes to our judgments of others. Jesus made it very clear that we incur certain responsibilities when we judge others. To the extent that we judge others, we will be judged by God (which is what Jesus meant when he said, "Judge not, that you be not judged"), so we must strive to be as critical of ourselves as we are with respect to the sins of others. We must seek to be people of integrity. We must ruthlessly root out hypocrisy in our own lives. No one does this perfectly, but it should nevertheless be our constant goal.
We should also seek to make judgments which are not arbitrary, but which in fact can be defended on the basis of reason, on the basis of God's word, and on the basis of the truth about particular people and particular situations. We should remember that our judgments are themselves subject to judgment by others and, far more importantly, by God.
Humility is essential. We must not claim to know more than we actually know. That's why we must leave final judgment up to God, knowing that things are not always what they superficially appear to be.
However, the need for humility should not be used as a lame excuse for failing to take a stand against evil and wrongdoing. Our judgments may be imperfect, but that does not change the fact that we are obligated to take a stand against such deeds.