seemingly religious concepts like izzat
It's not a religious concept at all, it is entirely secular. It is narcissism. Cluster B personality types are akin to a cancer in society. If they are not resisted/rejected, they will grow in power and pass on traits to new generations and normalize their selfish perspective on interpersonal relationships. Due to the lack of resistance against evil, the next generation becomes more narcissistic/sociopathic than the former, and so on. After many generations, it becomes such a deep-rooted part of the culture of that area that nobody remembers a time where it wasn't like that.
It is a cancer that has metastasized in many societies over human history. Pagan customs like "Hinduism" (which is just a catch-all word used to describe the many local pagan customs of India) pretty much operate on a "make it up as you go along" basis. This is easily weaponized by dark triad individuals, which is why pagan societies (of which India is the largest in our modern era) are never able to rid themselves of this cancer. Their entire belief system was built by, and built for, antisocial personalities.
Most of the major world religions, Bhuddism being the most well-known for this, became popular because they gave people a way out of this "izzat game". Christianity in India spread similarly, as it is mostly followed by low-caste individuals who wanted out of the game, since they were born into the losing rank. There is an Arabic term "jahiliya" which is loosely translated as "ignorance" but it specifically describes peoples who are tribalistic and obsessed with keeping score. The concept of jahiliya posits that living life by the rules of keeping izzat is a form of ignorance and that the enlightened person does not participate in such things, even if they live in a society that is dominated by it.
It is easy enough to see why Hindus are so anchored to the concept. The reason you will see Christians, Bhuddists, Muslims, Sikhs, etc. in India also playing the izzat game is because they don't know why their ancestor converted out of Hinduism in the first place. They don't have a proper appreciation or understanding of why they're not Hindu and just copy the norms of the predominantly-pagan society they live in. This is why new converts (to any major religion) tend to be a lot more adherent to their chosen faith than those born into it. They had a reason for converting, while those born into a faith tend to not understand the nuance behind why their family ended up a part of that faith in the first place.
A non-India example of this would be the Pashtun people (major ethnic and cultural group of Afghanistan + surrounding countries). They were pagan people who converted to Islam but never actually changed anything about their culture. They continue to abide by a code of conduct that they call "pashtunwali", which is extremely tribalistic and obsessed with score-keeping. This is why, in order to "keep izzat" (honour), they will murder their women over anything that is deemed shameful according to pashtunwali. I'm pretty sure that the persian word "izzat" was actually used by the Pashtuns before it was co-opted by the Indians.
They will try to legitimize their barbarianism by saying it is a part of their religion, but that is a performance for them as well. Narcissists love appearing to be religious. It is the easiest way to gain respect in society, and scratches their God-complex itch. They can justify anything with "well she was a sinner" or "God allowed it to happen" or "you must forgive me or else you go to hell" or "honor thy mother". Izzat is not religious, and the reason it has been allowed to proliferate for as long as it has, is because of people twisting religion to justify its existence.
