Agar koi musalman apne faida ke liye kuch logo ke samne jisme musalman aur hundu dono ko ye batae ki wo hindu hai aur khud ka naam bhi hindu batae aur ye kosis karta rahe apne harkato se ki wo hindu hai taki shak na ho ki wo musalman hai to kya aisa admi mjsalman raha aur agar aisa admi ka nikaah ho jae to kya uska nikah valid hoga.
For someone to state that he belongs to a different faith group would constitute disbelief, and even imitating other faith groups, when done without any serious need or compulsion, can be blasphemous in nature. The Honorable Imām Ahmad Raza Khan writes:
اس قوم کومحبوب ومرضی جان کر اُن سے مشابہت پسند کرے یہ بات اگرمبتدع کے ساتھ ہو بدعت اور کفّار کے ساتھ معاذاﷲ کفر
To consider that group of people beloved and desirable and then to prefer to imitate their ways, if this [imitation] is done with [a group of] innovators, then it is considered innovation, and if it is done with disbelievers, then it is considered, Allah forbid, disbelief. (Fatāwa Riḍawiyya, 30 Vol Ed, Vol 24, pg. 113)
This imitation applies to actions that are specific to that faith group, such as wearing clothes or performing customs that only they perform. It is written in “Minh-ur-Rawḍ-il-Azhar”:
وإن شدّ المسلمُ الزنّار ودخل دارَ الحربِ للتجارةِ كفر، أي لِأنّه تلبسُ بلباس كفرٍ من غير ضرورةٍ مُلجِئةٍ
If a Muslim ties a zunnār and enters a land of enemy combatants for the sake of trade, he will be considered a disbeliever because he wore the clothes of disbelievers without any serious need. (Minh-ur-Rawḍ-il-Azhar Sharḥ-ul-Fiqh-il-Akbar, Faṣl fi’l Kufr Ṣarīḥan wa Kināyatan, pg. 304, DKI Beirut, 2016)
If someone indeed has said these types of things and has actually done these types of actions in order to further himself or for his own benefit, then he should make tawba, repeat his kalima, and repeat his nikāḥ. Marriage with such a person would not be allowed until and unless he were to recant these statements and actions of his.
Allah knows best