What if we are to love the sinner for the sinner has a good side too?

Love the sinner and hate the sin is the Church's cosmetic. It covers up the flaws in the hideous philosophy of Catholicism.

The saying is nearly always given in the form of a command. When that happens, it does not really help at all. You would need to show people how to love the sinners and hate the sins. Commands are about forcing and pressuring people. Commands are veiled threats.

There is another way the command is put, “Love the sinner for see the whole person and not just the hateful sin which is only a small part of them”. It is denial of the obvious fact that once you sin you can’t do real good and all is sin and that sin or evil reflects the kind of person you are. You do evil because you are evil. It is actually worse to do good in a state of sin than to do harm for the person who pretends to love is worse than the one who brazenly hates. At least the brazen one sees the evil in all its horror and can make informed decisions about what to do.  Acting good and not being really good is more seductive and self-deceiving than open evil. To do false good soon makes you unable to see how sinful you are and Jesus said that this kind of sinner is the worst off and needs the most help. He spoke to such sinners scathingly even without provocation and his excuse was that it was the only way that might make them see (Matthew 23).
 
The Roman Catholic Church teaches that you can commit something called mortal sin. This is a sin that implies total rejection of God. You expel the saving presence of God from yourself. Those who die in mortal sin go to Hell for they are separate from God and so can't go to Heaven for God lives there. The good works of a mortal sinner deserve no blessing from God. The works are sins themselves for the sinner is only desecrating the good by doing it without reconciling with God. To love a mortal sinner would be then to love something that there is no moral good in. You cannot love sinners and hate their sins for it is not sins we are against but bad people. Those who hate sin because it insults the God of infinite love and so is very serious cannot love the sinner. They say they can and do but they are lying. The doctrine of mortal sin prevents you from looking at the good side of the person. The good side of the mortal sinner is dangerous for it is not really good and the more good the mortal sinner does the less likely he or she will be to see how much he or she needs to correct their sin and make peace with God. The good side cannot be praised by the true Christian. Instead the sinner has to be despised. God has to be loved so much - indeed totally - so hating those who loathe him or don't take him seriously or who don't appreciate him, ie mortal sinners, would be inevitable. You cannot love God and love the mortal sinner.
 
Nobody really wants to hate for hate is its own punishment and is less selfish. The evil person then will do good to mask his hate and to soften some of its effects. He can end up in denial about how much he hates.
 
You may say that you mean, "I disapprove of the wrongdoing and of the sinner as far as he or she is a sinner but there is so much I approve of so I am not against the person." Suppose that is true. Then you are against the person a bit. What you say is admitting that you hate and disapprove of the person who has hardly any good qualities. If a totally evil person existed you are saying you would hate them .
 
If I tell you I love you for you have some good points though you have sins too, I am saying that my love for you is conditional. If you become bad to the core I will not love you and I will hate you or not care what happens to you. I love the good you do and not you as a person.
 
Does the attitude, "I love you dear sinner because I am a sinner too and there is goodness in us that is greater than any of our sins", really come across as love? It plainly admits, "Dear sinner if I decided you were completely sinful or if you become completely sinful and worse than me I will not love you. I only love you based on my assumption that you are no worse than me."
 
If you mean what you say you mean, then you are failing to love the sinner and hate the sin.
 
The teaching that we must love the sinner and hate the sin because we are sinners ourselves suggests that hating the sinner is good but only if you are not a sinner! It involves wishing you were in a position to be able to hate the sinner!
 
The idea that a person should be loved despite their sins means the love is grudging and conditional. If I say, "I love you sinner but... and I hate your sin" then you do not really love the sinner because there is a but there. Thus it is only fair for people to be sceptical when you say that your hatred of their sin isn't hatred of them.
 
If a battered wife or partner says of her man, "He is not all bad," she is trying to protect herself from admitting how dangerous he is. She is trying to make out that the goodness in him gives her reason to hold that he is worth staying with. She protects herself from the trauma and uncertainty and sense of failure that comes from walking away. She protects herself from admitting that she is complicit in what he does for she does not protect herself from him. She protects herself from feeling guilty as a result of that. The guilt will be particularly strong if she admits to herself that she is failing to protect their children. What if she ends up in hospital at her man's hands or dies? What if the children suffer that too? She will be inclined enough to justify staying with her man on the basis that he has some good points without religion presenting her with a God who requires that she look at the good and forget the bad. It will take her longer - perhaps all eternity - to wake up and smell the expresso.
 
It is better for religion to collapse than for it to make it a divine law to declare people not all bad and thereby bring tragedy to that woman and her children.
 
If you identify a person as a sinner you are defining them by their "wrongdoing." It is wrong for the same reason as calling somebody disabled instead of calling them special needs. Admit that you are seeing them as a sinner and blinding yourself to any other side of them.

To call a person a sinner is to browbeat and humiliate them and nothing more. It is worse and more judgmental than calling them irrational or negative or stupid. Why not concentrate on the fact that sinners attempt to do good (even if it is the incorrect kind of good). The bank robber may rob for he wants his kids to have a good education. Condemning sin is supposed to be about love but it cannot be. Love the sin and hate the sin is unworkable for it is based on an incoherent "morality". Praise the sinner for attempting to do good by the sin and see the sin as an error. Praise the person and accept the person and thus empower them to make amends and do better.

Seeing too much good in a bad person makes you too slow to see the deal-breaker.  Time passes by and more harm is risked and done.  Believing that God is more powerful than this person's evil encourages that.  Believing that God has no fear of evil and bad people has its casualties.  People are in their graves over it.