A verse in the Book of Hoshea (14:3) states, "U'neshalema Farim Sefatenu" – "We will compensate for the cows with our lips." This means that in the absence of the Bet Ha'mikdash, when we are unable to offer sacrifices ("cows"), we can attain atonement with our lips – by reciting the sections of the Torah that discuss the sacrifices, as through this recitation we are considered to have actually brought these sacrifices. The verse mentions cows, even though other animals were also offered as sacrifices. The Ibn Ezra (Spain, 1089-1167) suggests that since the cow is the biggest animal offered as a Korban, the verse specifies this animal, expressing the idea that even the large offerings can be substituted nowadays with our mouths. Others suggest that the reference to cows alludes to the sin of the golden calf, the grievous sin which our ancestors committed that requires atonement. Finally, there are those who explain that this refers to the situation where the entire nation inadvertently commits a severe misdeed based on a mistaken ruling of the Sanhedrin, a situation which requires the offering a cow for atonement ("Par He'alem Dabar Shel Sibur"). The point being made is that we have the opportunity to attain atonement even for grave sins despite the absence of the Bet Ha'mikdash, through the recitation of the sections of the Torah dealing with the sacrifices.
A story told in Masechet Shabbat (12b) seems, at first glance, to contradict this concept. The Gemara there discusses the enactment legislated by the Sages that one may not read by candlelight on Shabbat, as he might tilt the lamp to move the oil toward the flame to make it steadier, which would constitute an act of Shabbat desecration. Rabbi Yishmael Ben Elisha felt confident that he would certainly not make the mistake of tilting the lamp, and so he read by the light of a candle on Shabbat. He ended up mistakenly tilting the lamp. After Shabbat, he wrote in his ledger that when the Bet Ha'mikdash would be rebuilt, he would bring an animal as a Hatat (sin-offering) to atone for this inadvertent violation. It seems that Rabbi Yishmael was not able to atone for this misdeed by reciting the section of the Hatat; he needed to actually bring the sacrifice in order to attain atonement.
One explanation might be that reading the section of Korbanot (sacrifices) is effective if one never has the opportunity to actually offer the required sacrifice. But if a person has the privilege of living to see the rebuilding of the Bet Ha'mikdash, then he must offer the sacrifice even though he had recited the section in the Torah.
By contrast, the Sapihit Bi'dbash (Rav Hiya Pontremoli, Turkey, 1764–1831), citing the Ma'abar Yabok, asserted that a sin committed during the time of the Bet Ha'mikdash is more grievous, and thus necessitates the actual offering of a sacrifice. After the Temple's destruction, sins lack the same level of gravity, and so they can be atoned even with the recitation of the Korbanot. However, this view appears irreconcilable with the Gemara's account of Rabbi Yishmael, who was obligated to bring a sacrifice for an offense committed after the Temple's destruction. Moreover, the Arizal writes that a person must fulfill all 613 Misvot, and so souls will need to be reincarnated and return after the Bet Ha'mikdash is rebuilt so they can fulfill the Misvot that require a Bet Ha'mikdash. This teaching, too, implies that reciting the Korbanot is not considered equivalent to the actual offering of the sacrifices.
A more compelling approach was advanced by the Petah Ha'debir (Rav Haim Binyamin Pontremoli, Turkey, d. 1873), who distinguished between the atonement achieved through the offering of a sacrifice, and the Misva to offer the sacrifice. Reciting the verses that speak of a required sacrifice suffices to atone like that sacrifice, but it does not suffice to satisfy the halachic requirement to bring that sacrifice after committing a misdeed. Therefore, even though Rabbi Yishmael could earn atonement through the recitation of Korbanot, he still bore the obligation to offer a sacrifice when the Bet Ha'mikdash would be rebuilt. Likewise, the Arizal taught that one will have to return after the restoration of the Mikdash to fulfill the Misvot of the sacrifices that could not be fulfilled without a Temple, even though atonement can be achieved even in the absence of the Bet Ha'mikdash, through the reading of Korbanot.
One might wonder, then, why we do not read each day the entirety of Parashat Vayikra, which goes through all the different sacrifices which an individual can bring and those which one must bring on certain occasions. If reading about a sacrifice earns a person atonement as though he actually brought the sacrifice, then it would seemingly be recommended to read this entire Parasha each day.
Some explain that one attains atonement for his misdeeds through Torah study, and so it is not necessary to read the sections of all the sacrifices every day. Rabbenu Yona (Spain, 1200-1263) writes that when a person makes the decision to perform Teshuba (repentance), he should increase his amount of Torah learning; if he had been accustomed to learning one page a day, then he should learn two pages a day, and so on. This is because Torah study has the ability to erase guilt for one's misdeeds. This is why the blessing in Shemona Esreh in which we beseech G-d to help us repent begins, "Hashibenu Abinu Le'Toratecha" – "Return us, our Father, to Your Torah." As Torah learning is a crucial element of repentance, we ask Hashem to draw us closer to Torah study so we can repent properly. This concept has been understood on the basis of the laws of "Kashering" utensils. The basic principle of "Kashering" is that a non-kosher flavor is expunged from a utensil through the same medium through which it was absorbed. Thus, utensils that were used to cook non-kosher food through direct exposure to fire must be directly exposed to fire to eliminate the forbidden taste so they may become permissible. The Yeser Ha'ra (evil inclination) leads us to sin through the "fire" of forbidden desires, and so we cleanse ourselves from wrongdoing through Torah learning, which is likened to fire. Therefore, some Rabbis explained that it is preferable to immerse oneself in Torah learning to achieve atonement, rather than spend time reading the sections of the Korbanot.
Rav Haim Palachi (Turkey, 1788-1868) explained that reading all the sections of the Korbanot is unnecessary because we recite the chapter of "Ezehu Mekoman," which goes through all the various kinds of sacrifices, and this is sufficient for us to be considered to have offered any sacrifice we are required to bring.
Another approach was taken by the Hida (Rav Haim Yosef David Azulai, 1724-1806). We are required to recite 100 Berachot each day, and we also recite each morning Baruch She'amar, which contains eleven expressions that begin with the word "Baruch" (not including the two instances of "Baruch" that begin and end the concluding blessing of Baruch She'amar). These 111 blessings, the Hida writes, correspond to the 111 verses of Parashat Vayikra, and by reciting them we are considered to have recited all of Parashat Vayikra.
This discussion underscores for us the importance of reading the Korbanot section each morning. As we have seen, this recitation is not simply an admirable and worthwhile practice; it actually provides us with atonement as though we brought the sacrifices in the Bet Ha'mikdash. Therefore, one should make every effort to arrive on time in the synagogue so he can recite this section and reap the great benefits that it offers.