According to Islam, marriage and establishing the family enjoys a special importance because it is a means through which one can keep away from sins and control his sexual instincts, thus he can remain in peace and move towards religious perfection. Monasticism (renouncing worldly pursuits) or living a life sequestered from the world has been reproached as it is believed to be against seeking perfection and attaining prosperity. According to Islam, marriage is desirable and recommended by itself but if a person is in need of marriage and is afraid that he may fall into haram, then marriage becomes obligatory on him.[1],[2]

The following points are necessary to be mentioned concerning your question:

According to Islamic Shari'ah, forbidden marriages are restricted to the following:

1. Maharem [3] 2. Married woman, 3. Wife's sister, 4. A woman who is in her waiting period, 5. Sister of a man who has committed sodomy, 6. A woman who is not from the People of the Book, 7. In the state of Ihram of Hajj, 8. Permanent marriage with a fifth woman.

Hence, if one is not afraid that his faith may be weakened or he is not likely to be led astray, there would be no problem in the marriage of a Shia with a Sunni especially when there is the possibility that the other party may be led to the school of Ahlulbayt (a.s.).

The following answers by grand Shiite jurists can serve as good proofs:

Question: What is the Islamic law concerning marriage between a Muslim and a non-Muslim or between a Shia and a Sunni?

Late Grand Ayatollah Fazel Lankarani: It is not permissible for a Muslim woman to marry a non-Muslim man and a Shiite woman’s marriage with a Sunni man is makrooh (abominable). A Muslim man can contract temporary marriage with a non-Muslim woman and there is also no objection to a Shiite man marrying a Sunni woman.

Late Grand Ayatollah Bahjat: As for the first part of the question, there is no problem in contracting temporary marriage with a woman from the People of the Book. As for marriage between a Shia and a Sunni, it is not permissible, as a measure of prescriptive (taklifi) precaution, for a Shia girl or woman to marry a Sunni man.

Grand Ayatollah Sistani: It is not permissible for a Shiite woman to marry a man from the People of the Book. If a Muslim man wants to contract temporary marriage with a woman from the People of the Book, it is permissible but if he is already married to a Muslim woman, it is not permissible for him, as an obligatory precaution, to marry a woman from the People of the Book even if his Muslim wife consents to it. As for marriage with a Sunni, if there is the fear that one might be led astray, it is not permissible.

Grand Ayatollah Makarem Shirazi: It is not permissible for a Muslim to marry a non-Muslim and there is no problem in the marriage of Shiite men with Sunni women. As for Shiite women’s marriage with Sunni men, there is problem in it because of the women facing the danger of getting misled.

Note: It is not permissible to marry the followers of some sects likes the Ghalis (or Ghulat), Nasibis and Kharijites who consider themselves as Muslims but in reality they are not Muslims.[4]

As for your mother’s saying about the Sunnis in general and the caliphs in particular, it is necessary to note that:

2. Shia believes that in order for a person's personality and character to be assessed and known, it is necessary that his conducts be properly examined and that his title or rank should not hamper or impede an investigation. Although being a companion of the Holy Prophet, peace be upon him and his family, is a matter of great pride, it does not imply that we should overlook his errors as we see that the Holy Quran has vividly reproached some of the Meccan migrants and the Medinite supporters for their mistakes.

Following the demise of the Holy Prophet (pbuh), a situation came into being as a result of which the Commander of Faithful, Ali (a.s.) who had been appointed by the Prophet (pbuh) as his successor was deprived of his right to the caliphate. Thus, during the period of Abu Bakr, Umar and Uthman, he was made to keep aloof in his house. But they sought his advice as and when they needed it. Indeed, for the good of Islam and Muslims especially the downtrodden, Ali (a.s.) despite being dissatisfied with the performance of the caliphate, never denied his advice to the caliphs. For example, in some battles such as the battles with Persia and Rome, the Commander of the Faithful (a.s.) was consulted and he gave his suggestions despite being absent from the wars.

Without doubt, if the Prophet (pbuh) were alive or if Imam Ali (a.s) would have taken the caliphate, the conquest would not have taken place in the manner that they did. That is to say, the wars and conquests were not approved of by Imam Ali (a.s.) in an absolute way.[5]

3. One of the most important wajib acts that has been mentioned in the Quran after believing in one god and rejecting paganism is honoring, respecting and obeying parents. The late Allamah Tabatabei says: "After the belief in the one god, respecting and obeying parents is one of the greatest wajib acts[6] and there is no difference whether the parents are believers or disbelievers in terms of being obeyed and respected; because the Quran has mentioned doing good to parents and respecting them in a unconditional form: "you shall be good to the parents".[7],[8]

Conclusively, there is no problem in the marriage by itself, as we stated above. If possible, try to give priority to your mother by getting her consent. In case, she is not agreeable, you should choose a more appropriate option. We recommend you to try to get her consent. (Obviously, mother’s consent and her good wishes for her child have significant impacts on his success and progress.) Finally, if you have chosen a girl whom you believe to be the most suitable person and the most appropriate one and you are in a position that if you do not take action for marriage, you are likely to fall into haram, you can marry the girl in accordance with the Shari’ah rules prescribed for marriage.