Welcome to the asylum. Enjoy your stay.

In my experience, I've never had a romantic relationship with a believer that was successful. Invariably, my atheism became an issue for them. Despite initial claims that it didn't matter, and that my non-belief would be respected, it was always later a problem for them.

Families always have a HUGE impact.
They always inject their religious beliefs into a marriage. If your partner doesn't love and respect you enough to stand up to the religious demands of family, you are not going to be permitted to live your life as you see fit. They simply will not have it.
That includes how you will raise children. They WILL constantly be trying to force their beliefs on how you raise your kids. They WILL always be undermining your wishes. There is no way around that. It WILL happen.

I know you think leaving is impossible, but it is not. You absolutely CAN do it.
It will be hard, at first, but you'll be better off living your life for yourself, than to be continually compromising to accommodate his (and his family's) demands and expectations.

If you do choose to leave, do it as soon as you can.
Whatever you do, DO NOT MARRY this person, or have children with him.
If you do, you will regret it.
Love does NOT conquer all. That is a FACT.

Live for yourself.
I wish you well going forward.

The main question you have to answer, is. Will the differences lessen or get deeper when once you are married ? Because if, as I suspect, reading what you write, they will grow, then however hard it may be, you have to make the break and walk away now. It is not a good idea to marry at all if you have any doubts. You may have, by now, invested a lot of time in this man, but although you do not state your age, I suspect that you will probably be quite young, and although it may seem that you will be giving up a major chance in life, life is a surprisingly long thing, and often offers far more opportunities that the young think it ever will.

And now I will say something with a strong sexual bias. Which is that, neither marriage nor religion are noted for being especially kind to women, and generally speaking if anything goes wrong, it is the woman who suffers most. Therefore, do what you think is good and be brave, but do think long and deep, including asking yourself, what this man's true motives for his religion are, and how he expects you to behave towards it after you are married. Simply ask him, and you may get an answer you like, which is fine, but if you don't, or you get a vague or evasive answer, then go. There is no risk in asking him because, it is better to find out now, while you still can part easily, than later.

I have a very strong opinion on this subject. Don’t get married and leave the relationship. This is based on over 50 years of experience. When my wife and I first got masked, she was a non practicing and I was a secular Jew. The Christian family gatherings were always uncomfortable for me but tolerable
Fast forward, I’m now an atheist but have deep cultural roots. My wife converted to Judaism—Reform and became an Uber Jew. The issues: she got on the temple board, became VP, and the President. Being President is a thankless job and a year from hell. Add to that the money she’s donated to the temple—huge sums. Then there are the holidays she participates in and wants me to be part of them.
Add this all together and it’s high stress
So get out while you can

I've seen all sorts of relationships work and the one thing they have in common is a MUTUAL deep respect for the other person and their beliefs. If you haven't got that, you have nothing of value and you certainly don't have a basis for a marriage.

I'm not sure how you'll succeed going into this marriage. It's more likely he will listen to his family, more than he's going to follow your wishes. The kids will have hindu names and hindu upbringing if his family have their way, and there's no way his parents will agree to a non hindu marriage without all the marriage rituals as per hindu custom. I'm sure you suspect this. I doubt they'll agree to anything otherwise. Also his a son and they're going to want him to follow hindu custom. You said he's religious. How is that going to change when you get married? I cannot see how living in Pune is going to make it any easier. Also when your kids are born, his family will be there doing prayers and all else. Have you considered moving to another city or out of the country to live your own lives? Is that possible? where you live your own lives away from family, where you remain Atheist, but you're already concerned his religion is getting in the way so how is that going to work? I gather you know the answers.

If you question a marriage as much as you do, I wouldn't hold out high hopes of a lasting marriage.

I couldn't do it and wouldn't try again. Depending on how religious the person is, it can be akin to living with a person with severe schizophrenia who won't take their meds.

If you’re not prepared to play the role that marrying into his family will bring upon you, don’t marry him. The relationship would only be an unhealthy one. Certainly not a good environment for raising children.
You may see walking away from this relationship hard because of the time you have given to it. But how hard will it be living a lie? How hard will it be ending the relationship when you have children together?

Clearly, his views do bother you and there seems to be no reason to think that his or your views are ever going to change to accommodate both of you in a marriage. Once you are married to him you will be part of a larger family and all that it entails.

It is one thing to have friends who hold religious viewpoints and with whom there is no requirement to live together but it would be quite another thing to live with them.

Given your statement above I am inclined to think that there may be other unstated factors that may influence your final decision. Compromise? A compromise is usually an uneasy temporary truce and not a long term solution. I would think it over very carefully before making a decision.

I really don't know what to say in your case. These things are very hard. I think it's better both of you to confront each other about this to see if there's a way to make it work. People sometimes can be very surprising for the negative and for the positive. If no solution can be found, you will know where each other stands. With this, be ready for the best and for the worse. Good luck for your situation, I hope it turns out well for both of you.

Just one question: can you continue to respect & admire someone who believes stuff you think is silly/stupid/untrue? ( and how about if he is adamant about making your children believe them?)
I personally could not & therefore would know the relationship is doomed!

As long as there's a subject, a big one at that, something will always be missing in the relationship. Marriage often changes the relationship and little things can start to rankle. A major item + time will equal extreme frustration and unhappiness. When I met my late partner (a long distance relationship) I had 3 must have items - willing to change location, no religion and vegetarian. It was a match on all three counts and it was the most beautiful relationship I could ever have imagined.

I'd get out of India, soon to be the most populous country on the planet. Horrible caste system. Brutal attitude towards women. Don't waste your education.

You've not stated your age or why and how it is that you are firmly atheist. Nothing there about what you as an individual want to get from and contribute to life. That kind of information would make anyone who's experienced long life better understanding. What you have included doesn't look good at all for building a life together with another person. The saying is 'opposites attract'. To whatever extent they do, I think it has only fleeting value because likeness in attitudes and values is vital to stability.

Like Annie said, I must absolutely agree, if you can support and admire him it's puzzling how that happens. Admiration in particular for oneself and the other is such a necessary element for both people to form a close bond. The other elements are love, respect and trust. Without feeling these things I don't know how, as you put it, sense that 'everything is great'. Marriage aside, my experience and study doesn't square with inability to surrender completely to that other person for 'everything to be great'...

This is where knowing things like your age, background etc. could be helpful. Sometimes when we're young, raging hormones influence us into believing that what is certainly pleasurable is 'great'. Time and living often reveal what great can be if one is successful forming a bond within which one CAN totally surrender to someone loved, respected, trusted and admired.

The man you describe sounds like someone trapped (voluntarily or involuntarily) within family and cultural dictates that he allows to determine his ways of living. You also mention 'years of relationship' without a number. There is no such thing as an investment in a relationship unless it's basis is one like a business deal; a trade situation in which parties make commitments, promises, assurances, sometimes property, tokens etc. Many marriages/relationships function for better or worse (like the ceremony says) but not necessarily in happiness. Such 'marriages' aren't founded on trust, but lack thereof; hence the necessity for assurances and commitments. Adversarial foundations can work in business and politics but they are not the stuff of close, loving, trusting KNOWING bonds.

"Truth is the daughter of Time." I taught my daughters that principle to apply to ALL relationships/friendships. If people don't allow time to really know the other person, fantasies and wishful thinking automatically fill-in, between what one does know about the other.

Children? With such a low regard for him in so many ways it would be foolhardy and doom you to bitterness and regret whether a marriage eventuated, lasted or didn't. They'd be hurt even more.
Marriage is ironically more strongly advocated by women than most men. It's an institution in which the roots, philosophically and culturally are deeeply male dominated; modern 'family law' notwithstanding.
Historically a female moves from her father's/clan's ownership to become a ward of her new male owner. Like his other property she and her progeny are branded like cattle with his name.

A woman independent enough to begin her intellectual emancipation as atheist doesn't sound like a good candidate for making a deal with someone with 'old world' ideas about religion OR women and children.

If you are as young as you sound, give Time a chance. She is very kind and will take good care of you by disclosing artifice and revealing truth in everything you encounter.

Your profile says you're open to meeting men and women, yet here you say you've been in a relationship with this particular man for years. Are you a bit of a free spirit? A bit of floating grass? If you are, I dare say don't hurt him (or anyone for that matter) by making a false commitment.

Everyone has needs, wants, desires, and expectations. You could ask that you each make a list in relation to marriage, children, and religious expectation, then have an honest discussion. If you can negotiate an agreement and be on the same page then you're good to go. If not then you may need to seriously think what a future with him will be like and ask yourself if this is really what you want.

If you find it hard to tolerate, then YOU are the intolerant .

I had a similar situation with my ex-wife but it was her politics rather than her religion that caused the problem. I was willing to overlook the differences but she couldn't let it go and it drove a huge wedge between us.

If the two of you can reach an agreement over the issue that's problematic between you where you simply agree to disagree and not discuss it further then it can be lived with, if not, it'll just continue to rankle each other until it becomes insurmountable and it breaks the relationship apart.

It's so much better to just agree to disagree and leave it at that but that seems to be impossible for some people. They'd rather sacrifice what they have than just accept a difference of opinion. Can you two just agree to disagree and not let it become a source of toxicity?

How . . . keep sane? I don't know. I suspect my father was not a theist but he followed my mother's: Church attendance and belief in god is mandatory. His good relationship with my mother lasted the rest of his life. He practiced and often repeated, (including any topic in religion) "Anything to keep the peace." I suspect avoiding any question of the existence of a magical sky wizard was his methodology to maintain a positive relationship with my mother.

I know of a Youtuber atheist who is married to his religious wife and he reports they get along and their marriage is good.

From my perspective, I consider respect and honesty essential virtues to establish a foundation for a worthy relationship. I can not respect a person who asserts faith (belief without evidence) claims as truth (based on facts) (demonstrable/testable). I find this position to be less then honest. I can not respect a partner who demonstrates those attributes. Likewise, I don't understand how a theist could respect an atheist who does not share their "Truth" based belief of an all powerful sky-daddy who will condemn the atheist (their marriage partner) to hell when their lifetime on earth reaches an end.

Good luck.

It doesn't sound like religion will stay out of your marriage. I have no idea, but I guess it's not just something that you would do. It should involve a compromise with both of you.