Deobandi is not part of the saved sect as they are not on the way of the Prophet salla Allahu alaihi wa sallam and his companions.

They are however Muslims in general but those who believe in things that
nullify Islam such as the belief that all what is in the universe is Allah, which is the belief of some of the extreme Sufis.

Having said that, marrying someone who is not committing any act or has any belief that gets him out of the fold of Islam is permissible. However, this is not recommended at all for people of Ahlu Sunnah and followers of the way of the Prophet salla Allahu alaihi sa sallam to marry people of innovation.

Kindly refer to the following link(s):

https://islamqa.info/en/22473

Shiekh , You said in a fatawa that , ” A Sunni Muslim cannot marry a Deobandi. ” Ya shiekh , I love you for the sake of Allah .In our country Bangladesh , Most of the people are following Deobandi Ulama.Seeing your fatawa many people are saying bad things . This hurts me most. Will you please clarify this fatawa . Is it haraam to marry a deobandi ? Or is it better not to marry a deobandi ?

Fiqh of Marriage | May 21, 2017 1:04 am
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shaykh My father remarried almost 2urs ago and he did this without any of his children and his first wife knowing. We have come to terms with this but he doesn’t call my mum unless he needs her to do a job, she lives in a freehold house with my brother but my dad gives her no money. He hasn’t seen her seen her in almost 2 years. Is this right?
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I was referred to a brother for marriage who is good in deen, character and finances. My mother has said nothing is wrong with him but she refuses to let us marry. My father is pleased with him.