1) At the end of his Sefer Ahavas Chesed, the Chafetz Chayim cites the Kuntres Marganisa Tava, which states (#17): "One should try to make life good for one's friend and pursue peace. Be careful about the negative commandment, 'Do not hate' (Vayikra 19:17). According to the Maharam Lublin, there is a prohibition against hating even a total Rasha before one has rebuked him, and in our generation there is no one who knows how to rebuke. Possibly, if he would have rebuked him, the Rasha would have accepted the rebuke, and it is his bad nature causing him to do the evil, as is stated, 'Do not judge your friend until you have reached his place' (Avos 2:4). Certainly one may not curse him, but one should pray for mercy that Hash-m will help him do a perfect Teshuvah."

2) The source of the Marganisa Tova's assertion, that in our generation there is no one who knows how to give rebuke, is the Gemara in Erchin 16b where (according to the Shitah Mekubetzes #7) Rebbi Tarfon said, "I would be amazed if there is anyone in this generation who knows how to give rebuke. If one says to the other, 'Remove the splinter from between your eyes,' the other will reply, 'Remove the beam from between your eyes!'"

3) Before I go further, I want to comment that there is a good reason for why the title of this question is Pesachim 113. I will, bs'd, refer to that Gemara later.

4) Back to the question at hand: The Chazon Ish (YD 2:28) discusses Halachos concerning a Kofer. He points out that there is a condition involved here -- namely, that the Kofer should not be ????, he was not "forced" into being a Kofer. The Chazon Ish cites the Rambam (Hilchos Mamrim 3:3) who writes that a Kofer is someone like Tzadok, who founded the Tzedukim (Sadducees) sect in the time of the second Beis ha'Mikdash. The Rambam writes that the first generation of the Sadducces are also considered Koferim, but the sons and grandchildren of these people are considered as "babies who were captured" by these erroneous sects. These later generations are considered as ???? -- as though they have been forced into their mistaken ways because they did not receive the correct upbringing. "It is worthy to return them through Teshuvah and attract them with words of peace until they return to the might of the Torah."

The Chazon Ish continues and cites the Hagahos Maimoniyos (Hilchos De'os 6:1) who says that one is allowed to hate such people only after they have rejected rebuke, and then he cites "Marganisa Tava" ("the good pearl)" that for this reason it is a Mitzvah to love the Resha'im nowadays because in our situation it is always like before rebuke, since we do not know how to rebuke.

5) Now to Pesachim 113b, mentioned at the beginning of this answer: The Gemara there mentions a contradiction between two verses. Shemos 23:8 states, "When you see the donkey of the person you hate." But how is one allowed to hate another? Vayikra 19:17 states, "Do not hate your brother in your heart"! The Gemara answers that he is allowed to hate somebody whom he saw committing a transgression of Ervah, immorality. This Gemara is cited by the Shulchan Aruch (YD 272:11) who states that he alone saw another person commiting a transgression (the Shulchan Aruch does not state specifically that it was Ervah, as in the Gemara, but rather any transgression) and warned him not to do it, but the perpetrator did not retract. Under such conditions it is a Mitzvah to hate him.

The Shulchan Aruch does say that he must first warn the transgressor, but how can this be reconciled with Erchin 16b where Rebbi Tarfon says that in his generation there was nobody capable of administering rebuke? The Shulchan Aruch seems to imply that even nowadays it is possible to warn him, but the Marganisa Tava and Chazon Ish understood that what Rebbi Tarfon said applied not only to his times but is true nowadays as well!

6) I want to suggest a very simple solution and say that the Gemara in Pesachim and the Shulchan Aruch refer to a specific situation where we know that the sinner is fully aware that he is doing wrong. He does not try to argue with the rebuker, but even so he says that he does not care. In contrast, the Marganisa Tava and Chazon Ish are referring to a more general phenomenon of sinners who, if they would be rebuked properly, may well turn away from their bad ways. The Chazon Ish mentions the fact that the offenders may not have received the good upbringing which would enable them to appreciate that what they are doing is so wrong.

7) Let me add what I find in the Tomer Devorah and the Tanya.

a) I found, bs'd, that the Tomer Devorah (by Rav Moshe Cordovero) writes at the end of chapter 2: "One should accustom oneself to internalize the love of people into his heart -- and even the evildoers -- as if they were his brothers, and even more than this, until he fixes the love of all people into his heart.... And he shoud even love the evildoers in his heart, and say, 'Who would give that they should all be righteous Ba'alei Teshuvah and all be great ones and desirable to the Omnipresent!'"

b) The Tanya (Likutei Amarim, ch. 32 on Ahavas Yisrael) writes: "What is stated in Pesachim 113b, that if he saw somebody sinning it is a Mitzvah to hate him, applies only to someone who is a colleague with you in Torah and Mitzvos, for whom he has already fulfilled the Mitzvah of 'You shall surely rebuke ?????' (Vayikra 19:17). The word ????? refers to ?? ???? ????? ?????? -- a person who is together with you in carrying out Torah and Mitzvos (see Shevuos 30a) but has not done Teshuvah on this particular sin. In contrast, somebody who is not your friend and you are not close to, about such people Hillel the Elder said, 'Be of the disciples of Aharon, a lover of peace, who loved people and drew them near to Torah' (Avos 1:12), which teaches us that even those far away from Hash-m's Torah and service should be attracted with strong cords of love."

According to this, that the Mitzvah of rebuking applies only to those who keep Torah and Mitzvos, and according to what I wrote above that one is allowed to hate a person only if he has first rebuked him, it follows that one should love even people who do not keep the Torah.

8) I should mention an important point that the Tanya makes after what I cited above. We saw above that the Tanya learns that the Mitzvah of rebuke applies only to people to whom has a relationship already. According to this, we said that one anyway has to love all those who are not so close, because one cannot give them rebuke and therefore one is re never allowed to hate them for their bad actions. However, the Tanya adds that even those people to whom one is close -- and one rebuked them for the bad things that they did and they still did not Teshuvah -- even though one has a Mitzvah to hate them, one also has a Mitzvah to love them! Both are true! One hates the bad things they do, but one loves them for the hidden good inside of them, which is a Divine inner spark which keeps alive their G-dly soul. One should also daven for them.

I should also add that the Shitah of the Tanya is quite similar to the opinion of the Sefer Chasidim, cited by the Mishnah Berurah in Bi'ur Halacha, 608:2, DH Chayav. He writes that one must give rebuke only to somebody with whom he is familiar, but if there is reason to believe that the rebuked may hate and avenge the ?????, one is exempt from giving Tochechah, rebuke.

9) We have been saying all along that if one cannot give rebuke to the Rasha, this means that one must continue loving him. It is worth looking at how the Maharal of Prague (on Erchin 16b) explains how difficult it is to administer proper Tochechah. According to the Maharal's text, it was Rebbi Akiva who said, "I would be amazed if there is anyone in this generation who is able to rebuke!" Rebbi Akiva said that the problem is not with the people who are being rebuked; the problem is with the people who are doing the rebuking. The ????? does not how to say things properly so that the sinner will accept what he says. A lot depends on how one gives rebuke. One requires extra wisdom, and great guile. How deep is what Rebbi Akiva said -- "I would be amazed if anyone is able to give Tochechah"! The sinner is already leaning towards the crime and if one wants to pull him out from what he has done one needs great wisdom. The Maharal concludes that one has to give good, true reasons and very good logic until it enters the sinner's hardened heart.

So if one does not know how to persuade the Rasha properly, one simply must carry on loving him!

10) To conclude this answer, and to show how closely related it is to Tish'ah b'Av which we recently experienced, I will make some comments, bs'd, about what Tochechah is. The Beis ha'Levi, Parshas Vayigash, explains what Chazal say in connection to Yosef revealing himself to his brothers, "Woe is to us from the day of Din; woe is to us from the day of Tochechah" (Bereishis Rabah 93:10). What is the difference between Din and Tochechah? The Beis ha'Levi (end of DH v'Es) writes that the word "Tochechah" is related to the word "Viku'ach" (argument). The person who gives rebuke "argues" with the sinner and proves to him ("l'Hochi'ach," also related to "Tochechah," means "to prove") from other things that he has done in the past that his excuses for doing what he is doing now do not really satnd up to logic and reasoning. This strengthens what I wrote above in the name of the Maharal of Prague, that Tochechah must be given in a very convincing and logical manner. If this cannot be done, then there is no Heter not to love someone.

This is what is stated in Sotah (49b), that before the Mashi'ach comes, there is no Tochechah. Rashi writes that there is no one who can "Yochi'ach," which can also be translated as "to prove." When the Mashi'ach comes, speedily in our days, and we get back the Beis ha'Mikdash, everyone will know the truth and will be happy at their ways being put right.

Dovid Bloom