أعوذ بالله من الشيطان الرجيم

بِسْمِ ٱللَّٰهِ ٱلرَّحْمَٰنِ ٱلرَّحِيمِ

As Salaamu Alaikum Wa Rahmatullahi Wa Barakatuh,

Based on your specific question and information provided.

Parents and Children have rights and obligations to each other under Islam. Parents might be concerned due to various risk factors in a Marriage between two sects, change of heart/belief after marriage, Belief of the grandchildren, who will raise the grandchildren in case of a divorce or death. Will the immediate / extended families and friends see it as a positive/supportive and allow the grandchildren to practice their belief or there will be negative impact on the children at a psychological level  and so on. People usually marry or prefer to marry within the sect. So the son is asking for an exception, Islam is a religion for all times, conditions, situations, concurrent / multiple marriages, and different types of marriages. So if something (in this case the “Marriage Contract” ) is allowed / permissible / Mubah (Optional / at your discretion) under the Jurisprudence, as it covers the general Muslims for all times and conditions. We have to consider others factors like Aqidah / creed , Islamic morals / ethics and other special circumstances specific to your situation.  In this case, the son has to use wisdom and address the normal concerns of his parents..

The Islamic Scholars have divided the Islamic teachings in three parts.1)Fundamental of Faith ( Belief / Aqidah),  2) Islamic Ethics / Morals, and 3) Islamic Law/ Fiqh / Jurisprudence.The “institution of  Marriage” is covered by all three.The “Marriage Contract” is cover by Islamic Jurisprudence.

From the Islamic  Jurisprudence perspective.

مسألة 215: يجوز زواج المؤمن من المخالفة غير الناصبية، كما يجوز زواج المؤمنة من المخالف غير الناصبي، على كراهة، نعم إذا خيف عليه أو عليها الضلال حرم.

منهاج الصالحين – السيد السيستاني – ج ٣ – الصفحة ٧٠

Minhaj al-Salihin – Sayyid al-Sistani – Part 3 – Page 70 : Edition 7:  Year 1998.

Rough English Translation( you should consult an Arabic speaking person or take it to your local Mosque to the scholar to explain the proper Arabic words/terminology/essence). :

“It is allowed for the believer to marry a woman from the other sect, (on the condition that she is ) not a Nasabi (Nawasib) and it is allowed for the believing woman to marry a person from the other sect (on the condition) he is not a Nasabi (Nawasib) , and it is  ( كراهة ) (Makrooh / Not recommended ). If there is  fear on him or her that they will be misguided ( go astray/ loose Imami Shia Faith/ Aqidah / Fiqh ) than it is  ( حرم) ( Haram / Forbidden ).

Updated explanation of the last sentence above (1) ( نعم إذا خيف عليه أو عليها الضلال حرم)

مسألة 215: يجوز زواج المؤمن من المخالفة غير الناصبيّة، كما يجوز زواج المؤمنة من المخالف غير الناصبيّ على كراهة، نعم يحرم إذا خيف عليه أو عليها من أن يؤدّي إلى الانحراف في العقيدة أو المنع من أداء الوظائف الشرعيّة وفق مذهب الإماميّة.

Rough translation of the highlighted text :

Yes, it is (Haram) forbidden if it is feared that he or she will lead to a deviation in the  ( العقيدة ) Creed / Aqidah  or prevent him/her from performing the Islamic Shari’ a duties according to the ( مذهب الإماميّة ) Imami school of thought ( Fiqh / Jurisprudence).
********************
Note: Nawasib (i.e. those who are enemies of (the Holy Imams (عليه السلام) and Sayyida Fatima al-Zahra (sa) ),  are  impure.

(*) can review past Q&A below.

والله العالم‎
(and Allah(awj) Knows best)
If you have further questions kindly contact us at (718) 297-6520 Ext 113 Monday to Saturday between 11:AM – 3:00 PM.

(*)

https://www.al-khoei.org/Questions/marriage-between-two-muslims-of-different-sects-aqeeda/

https://www.al-khoei.org/Questions/can-a-syeda-girl-marry-a-sunni-guy/