Marital Relations During Niddah

Shalom and blessings.

 Regarding those who were not raised on observance of Torah and mitzvot, and were not aware of the matter of niddah observance, it is considered inadvertent, and complete teshuvah is sufficient to correct the past. To complete the rectification, one may say the passage of the sin-offering, which would be in place of bringing a sin-offering sacrifice that would have been brought if they had sinned inadvertently in a sin whose punishment is karet. Even if the sin was committed knowingly, it is proper to note the appropriate path in the words of one of the greatest sages of the generations in his responsa Noda BiYehuda (first edition - Orach Chaim, siman 35), who wrote very fundamental things regarding rectifications for sins in addition to teshuvah. And this is his wording: What Your Honor asked of me, to arrange for this penitent a repentance for his transgression, and he mentioned that he is a very frail person who cannot tolerate the hardship of fasts and afflictions... It is difficult to ask me such a difficult matter, for I am not accustomed to answering one who asks me a question about something for which I cannot find a basis in the words of the Gemara and the poskim, because we do not find in all of the Talmud a set number of fasts, fixed days and measured days for each sin and transgression according to the severity of the iniquity. Rather, I say that all this is if fasting were something that blocks teshuvah, but in truth fasting is only a secondary matter to teshuvah, and the essence of teshuvah is leaving the sin, verbal confession with a broken heart, sincere regret, and drawing close with fervor to love the Creator, and that is teshuvah: that he return to Hashem and He will have mercy on him; and he shall return to Hashem, meaning that he cleaves to Him, but the other matters, fasting and afflictions, are not essential. And know that it is beyond doubt that teshuvah atones complete atonement, and this matter is well known in the Torah, Neviim, and Ketuvim, in both Talmuds, and in all the Midrashim, and the prophet says (Ezekiel 18), and when the wicked turns from his wickedness, etc. (there, 33), all his sins that he committed shall not be remembered for him, etc. And although in the four divisions of atonement Chazal said that if one transgressed a karet prohibition, teshuvah and Yom Kippur suspend, and suffering polishes away, meaning that suffering is the main atonement and it is impossible to complete the atonement without suffering, I say that it is true that suffering is needed, but Chazal already said how far the end of suffering extends: even if he put his hand into his pocket to take out three and only two came up in his hand. But regret, a broken heart, and tears are very necessary, and one who increases in hidden tears is praiseworthy. This is the end of his wording. But as I wrote, if the matter is that you were raised with a secular upbringing, your own teshuvah is enough in itself to atone and correct everything, and even to transform the sins of the past into merits. 

Success and a joyous festival - Menashe Yisrael